LEAFCUTTER BEES  &  CUCKOO LEAFCUTTER BEES

ID GUIDE TO WILD BEES - NEW YORK

LEAFCUTTER BEES  (Genus Megachile)

The name leafcutter derives from leafcutter bees' practice of using their sharp-edged mandibles to cut leaves and flower petals for transport back to their nests.  The bees use these materials to line the walls of brood cells containing the leafcutters' eggs.  Leafcutters are solitary; they construct individual nests in dead twigs, rotted trees and the ground.  They do not damage houses, do not swarm and are nonaggressive.
 

Female leafcutters have large, toothed mandibles; the number of teeth and sharp edges on their mandibles vary from species to species.  Those with more formidable mandibles cut leaves, and those with simpler ones trim more delicate materials such as flower petals.  According to Charles D. Michener, author of the 953-page The Bees of the World, the pieces leafcutters snip from plant parts tend to be nearly uniform in shape -- oval for constructing the bases and walls of their egg cells and circular for covering cell openings.  

 

Leafcutter bees are easily identified by their unique shape. They have wide, somewhat flattened abdomens that taper abruptly at the ends and broad, sculpted-looking heads with large jaws.  As shown in the photos here, female leafcutters carry pollen in a distinctive way that helps identify them -- on sticky hairs called scopae located on the undersides of the bees' abdomens, rather than on their legs. 

 

Male leafcutters lack scopal hairs and sometimes differ significantly in appearance from their female counterparts.  As shown in the photo strip below right, males tend to have hairier faces than females.  In some species, males' front legs may sport long hairs or be enlarged or brightly colored.

 

The various species of leafcutters range in size and general attributes.  Some are larger than honey bees, and some so small they elude notice by the casual observer.  Some are black; others are smoky-gray or black with pale stripes.  Some specialize in gathering pollen from a narrow range of wildflowers, and others are generalists.

Leafcutter bees are important pollinators of an extensive gamut of commercial crops, including alfalfa, carrots, onions, blueberries and cranberries, among many others.  Wild leafcutters are also responsible for pollinating a prodigious range of wildflowers and garden flowers.

Leafcutters belong to the genus Megachile.  Within New York alone, there are 10 subgenera (subgenuses) of leafcutters containing more than 20 distinct species.  Nine species representing 5 genera (genuses) have been found in Rockefeller State Park Preserve and Stone Barnes Center for Food and Agriculture.  They are shown below.

All photos (c) 2014 - 2017 Sharp-Eatman Nature Photography

Frugal Leafcutter Bee

Megachile frugalis
(Subgenus Sayapis)

2/5" to 1/2" (medium-sized)

The striped leafcutter species Megachile frugalis belongs to the subgenus Sayapis.  Leafcutters in this subgenus tend to be on the large side, and fairly slender as leafcutter bees go.  In The Bees of the World, Charles D. Michener notes that Sayapis leafcutters have parallel-sided bodies; this enables them to move easily through the narrow burrows they use when building nests. 

Identification Information:  The frugal leafcutter bee shown here is 1/2" long, about honey bee size. Megachile frugalis leafcutters have large black heads; black legs and antenna; and wings characterized as "smoky" in color.  Their bodies are black and the top halves of their abdomens are striped with bands of white hair. 

 

The undersides of females' abdomens are covered with long white scopae (pollen-collecting hairs) and are not striped. White hairs, intermixed with some dark hairs, also cover the bees' faces.  On females, the clypeus (located on the lower part of the face) is black.  The presence of dark hairs on the female bee's dark clypeus is a distinctive trait that aids in identification of this species.

 

Megachile frugalis leafcutters are associated with prairie and arid habitats.  These leafcutters are not listed in the Discover Life database as a New York species.  Nevertheless, these bees appear in the park in late June and July feeding on the variety of orange milkweed known as butterfly weed.  The bee shown here was identified by entomologist John S. Asher. 

 

These bees are documented pollinators of a range of wildflowers, including lemon bee balm; members of the pea family such as vetch, melilot and tephrosia; members of the aster family, such as heath aster; wild buckwheat; and prickly pear cactus. These bees also visit alfalfa and sunflower crops.

 

A variation of this species, Megachile pseudo frugalis Mitchell is found in the American southwest. Frugal leafcutters are preyed on by cuckoo leafcutter bees of the subgenus Synocoelioxys.  An example of such a cuckoo bee is shown at the bottom of this page.

A female frugal leafcutter bee

Hostile Leafcutter Bee

Megachile inimica 
Subspecies Megachile inimica sayi
 
(Subgenus Sayapis)

2/5" to 3/5" (medium-sized)

Like the two leafcutters shown directly above, the hostile leafcutter belongs to the Subgenus Sayapis and has the long, parallel-sided abdomen typical of this subgenus.  Megachile inimica bees are fairly large for leafcutters -- usually between 2/5" and 3/5". These bees have long dark abdomens striped with pale hairs and dark thoraxes and wings.  Females have pale scopal hairs under the first five segments of their abdomens, and dark hairs under the sixth.

Hostile leafcutters are widespread and important pollinators of wildflowers.  In our area, they are most commonly found on flowers of the Asteraceae family such as New England asters, rudbeckia, sneezeweed and sunflowers.  The bee shown here was found feeding in August on black-eyed Susans and on a variety of wild yellow daisy called verbesina or crownsbeard. 

Hostile leafcutter bees are solitary nesters that employ inventive  masonry skills  to construct their tubular brood cells.  In a seminal study of bee and wasp nesting behavior, the entomologist Karl Krombein wrote that he had observed hostile leafcutter bees forming cell partitions by combining circular leaf-cuttings with layers of sand and with small pebbles.

Identification Information:  The faces of male hostile leafcutters are covered with white hairs.  Males have three-toothed jaws and females four-toothed jaws. As illustrated in the photo strip at right, female hostile leafcutters have distinctive faces that distinguish them from the two Sayapis leafcutter species shown directly above  (frugal and pugnacious):  On the female hostile leafcutter bee, the clypeus (the face part above the jaws) comes to a low point in the middle.  The point is flanked on each side by a slight curve.

There are two subspecies of hostile leafcutter in North America – Megachile inimica sayi (shown here), found mostly in the north, and Megachile inimica inimica, found mostly in more southern areas than New York.  These subspecies are identical except for their coloring – the pale hairs of the abdominal bands and scopae are white in Megachile inimical sayi and yellowish in Megachile inimica inimica.  In the subspecies Megachile inimica sayi, both males and females have primarily black legs, while  Megachile inimica inimica males have reddish legs.

Pugnacious Leafcutter Bee

Megachile pugnata pugnata
(Subgenus Sayapis)

1/2 to 7/10" (females);  2/5 – ½” (males)
(medium-sized to medium-large)

Female pugnacious leafcutters have a wonderfully monstrous appearance:  their huge jaws are visible even to the naked eye.   If you grow sunflowers, you may be lucky enough to come upon one of these leafcutters. These bees are prized pollinators of commercial sunflowers.  They are also amenable to nesting in "bee houses" constructed of hollow reeds or tubes glued together, and thus can be lured to your backyard if provided with the right climate and food sources.

 

In the wild, pugnacious leafcutters build nests in pre-existing cavities made by insects or other animals. Females use their hefty jaws to cut circular discs from leaves; they then partition their tubular nests with walls made of the leaf-discs, chewed leaves and soil. The bees construct their nests so that the egg cells of male offspring are built at the back of the nest and those of female offspring at the front.

The pugnacious leafcutter bees shown here were found foraging in late June and July 2016 on purple coneflowers and milkweed in Rockefeller Park’s perennial garden.  Pugnacious leafcutters typically pollinate a broad spectrum of wildflowers and garden flowers in the Asteraceae family, such as fleabane, thistle, yarrow, coreopsis, blazing star, black-eyed Susans and dandelions.  The Discover Life database also records pugnacious leafcutters as feeding on snowberry and spreading dogbane. 

 

In addition to being excellent pollinators of commercial sunflowers, pugnacious leafcutters pollinate squash, melons, peas and caneberries.

Identification Information:  Like the frugal leafcutter bee above, the pugnacious leafcutter belongs to the subgenus Sayapis.  True to their subgenus, pugnacious leafcutters have abdomens that are slender and parallel-sided.   Female pugnacious leafcutters can be quite large – as long as 7/10 inches.  Males are smaller, usually 1/2 inch or smaller.

 

Female pugnacious leafcutters are best recognized by their enormous jaws.  The scopal hairs under the bees' abdomens are an eye-catching yellow, as are the bottom portions of the bees' legs.  The female pugnacious leafcutter bee also has pale hair on its face and cheeks that tends to obscure three large and distinctive toothlike projections under the bee's head.  The vertex (top portion behind the eyes) of the female pugnacious leafcutter's head is unusually wide .

Both males and female pugnacious leafcutters have black heads, bodies, legs and tegulae (wing bases).  Their abdomens are striped by well-defined bands of pale hairs. Males lack the proportionately huge jaws of the females, however. 

 

Male pugnacious leafcutters have distinctive forelegs:  as shown in the photograph and photo strip at right, the basitarsi the male bees' front legs are expanded, pale yellow, and adorned with long, yellowish-white hairs.

A female pugnacious  leafcutter bee

All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography

Megachile Addenda Leafcutter Bee
Megachile addenda
(Subgenus Xanthosarus)

2/5" to 1/2" (medium-sized)

Unlike the three leafcuters featured above, the Megachile addenda leafcutter bee belongs to the subgenus Xanthosarus.  Leafcutters in this subgenus tend to be large with thick heads and hefty bodies.  Their abdomens are gently curved rather than parallel-sided. 

 

​Megachile addenda leafcutters are known to pollinate blueberries and cranberries and are associated with areas where these are cultivated.  According to the Xerces Society's Attracting Native Pollinators, these leafcutters build nests in sandy banks adjacent to cranberry bogs all along the east coast. 

These bees also feed on flowers in the legume family (Fabaceae), such as clover, false wild indigo, vetch and leadplant.  Megachile addenda leafcutters have been found nectaring in early June on swamp mikweed and dogbane situated near spring-blooming blueberry bushes by Swan Lake. 

Most leafcutters in our area nest in cavities in wood or pithy plants.  Megachile addenda bees, however, nest in the ground.  In early June, 2017, an aggregation of more than one hundred bees occupied a nest site that had been used in April by unequal cellophane bees. The nest area was situated in a Rockwood Hall trail covered with small pebbles, paving stones and bare dirt.  Female Megachile addenda in this nest site could be observed making repeated trips to their holes, carrying leaves to line them with.  Several bees assumed control of two different entrance holes apiece to exit and access their nests -- as depicted in the photo above right.

 

There have been no reported sightings in the park of this bee species after late spring.  The best way to spot Megachile addenda bees is to look for small nest holes in bare banks and trail edges during early June, in areas where blueberries or legumes are growing nearby. 

Megachile addenda leafcutters are preyed on by immaculate cuckoo leafcutters (Coelioxys immaculata), which are shown farther below on this guide page.   In May, 2017, many  immaculate cuckoo leafcutters lurked outside of  the holes of the Megachile addenda aggregation established in the Rockwood Hall trail.  Occasionally the cuckoos could be spied slipping into the leafcutters' holes to lay their own cuckoo bee eggs.

 

​Identification Information:  Megachile addenda leafcutters are about honey-bee size or larger, with robust builds.  They are dark, with well-defined bands of pale hairs encircling their black abdomens.  Females have bushy white scopal hairs.  (The last segment of the female bee’s abdomen has black scopal hairs.)  As shown in the photo strip at right, the female Megachile addenda has distinctive mandibles with four teeth and a cutting blade between the third and fourth tooth. The male bee has a distinctive notch in the tip of its abdomen.  Both males and females have dark olive-green eyes.

Megachile addenda leafcutters are very similar to the species Megachile texana, which also nests in the ground.  Female M. texana and M. addenda are best told apart by minute inspection of differences in their mandibles.  Differentiation between the species may require expert assistance.  A cursory identification might be made by noting what plants species the bees are feeding on and what time of year they appear.  M. texana feeds on a much broader range of plants, is more common and tends to be visible late into the summer.

Black and Gray / Blueberry Leafcutter

Megachile melanophaea  / Megachile mucida
(Subgenus Xanthosarus)

1/3" to 1/2" (medium-sized)

All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography

Small-handed Leafcutter Bee

Megachile gemula
(Subgenus Xanthosarus)

1/3" to 1/2" (medium-sized)

Like the Megachile addenda bee above, the small-handed leafcutter bee  belongs to the subgenus Xanthosarus.  It manifests the traits associated with its subgenus -- a comparatively large size (1/3" - 1/2"), thick head, heavy body and an abdomen that is curved rather than parallel-sided. 

 

Female Megachile gemula are distinctive, because they have black scopal hairs on the undersides of their abdomens; the bees use these hairs to transport pollen.  The bee's tarsi ("toes" ) are short and slender, a trait that gives this species the name "small-handed leafcutter".

This black variety of leafcutter is quite plentiful in mid-June in the park and Stone Barns, where it appears feeding principally on orange butterfly weed. Small-handed leafcutters disappear from both locations by the second week of July.   ​Small-handed leafcutters are pollinators of wildflowers; of garden flowers such as roses and hydrangeas; of legumes; and of caneberries, blueberries and cranberries. 

Identification information:  The small-handed leafcutter has a black head and body; black legs; black antennae; dark eyes.; and a ruff of pale hairs on its thorax.  As noted, females have black scopal hairs under their abdomens. Male bees are somewhat smaller and less robust than females.  As shown in the photo strip at right, males have flamboyant white hairs on their forelegs.

These bees lack the well-defined bands of pale pair that appear on many of the leafcutter species shown on this page. Sparse pale hairs appear on the female bee's first and second abdominal segments, (T-1 and T-2), and the front of the third segment (T-3).  The female bee's hind segments (T-4 - T-6) are black.  Pale hairs also appear at least in part on the first four segments of the male bee's abdomen; the remaining segments are entirely black.

Megachile gemula females closely resemble those of two other leafcutter species of the subgenus Xanthosarus:  M. melanophaea (the black-and-gray leafcutter) and M. mucida (the blueberry leafcutter).  Expert assistance may be necessary to tell these species apart.

Female small-handed leafcutters and M. melanophaea leafcutters can be distinguished by minute differences:   the second segment of M. melanophaea's abdomen is covered with pale hairs.  On M. gemula, the second segment is pale with dark brown corners along the segment's sides.  M. melanophaea also tends to have some orange scopal hairs. Notably, M. melanophaea is a northerly species, found in Canada and New England.  The bee is not commonly seen in southern New York.

The differences between M. gemula and M. mucida females are even more subtle -- on M. mucica, the rearmost (topmost) tooth of the bee's mandible comes to a rounded point.  As shown in the photo strip at right, on M. gemula, this tooth looks lopped off or flattened.

A female small-handed leafcutter bee

All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography

A female Megachile addenda leafcutter bee in a nest with dual holes; she has just carried the leaf cutting above left to her nest.

A male Megachile addenda leafcutter bee

A female Megachile addenda leafcutter bee

Several species of leafcutters belonging to the subgenus Xanthosarus show striking sexual dimorphism.  Female Xanthosarus leafcutters are often black with dark legs, sometimes with pale hairs on their thoraxes or pale banding on their abdomens, like the female shown below right.  Males Xanthosarus leafcutters can look markedly different -- some have enlarged forelegs sporting extravagant long hairs and ornamented with pale-yellow, rust and black markings.  An example is the male leafcutter shown here at right.  The enlarged forelegs of such male leafcutters are used to cover the eyes of females during mating.
 

The male bee at top right has been identified as belonging to one of two similar-looking species:  the black and gray leafcutter (M. melanophaea)  or the blueberry leafcutter (M. mucida).  Back and gray leafcutters tend to inhabit more northern areas of the eastern United States.  Blueberry leafcutters are more common in the southeast. Our area is on the cusp of the northern and southern ranges of these two  difficult-to-distinguish species. 


The black and gray leafcutter, Megachile melanophaea, feeds on a variety of flowering plants, including azaleas,  bellflowers, spreading dogbane, penstamon, roses, vetch and caneberries.  It also has the distinction of being  a documented pollinator of slipper orchids (Cypripedium maranthos var. rebunense), which otherwise require pollination by queen bumble bees. 

Megachile mucida is a well-known blueberry pollinator -- hence, its common name.  This bee also pollinates bellflowers and members of the pea  family. 

 

Both the male and female bees shown were found resting on plants within a a patch of bellflowers, at Stone Barns Center for Food and Agriculture, in early June, 2016.

Identification information: 

Males:  Male Megachile melanophaea and M. mucida,share many identical traits:   they are both robust black bees with pale hairs on their heads, thoraxes and abdomens; enlarged forelegs adorned with long white hairs and  orange, black and pale markings; four teeth on each jaw; and green eyes.  Males of these two species are told apart by minute differences in the rims of the sixth segments of their abdomens (S-6).

 

Notably, males of at least three other species in our area bear similar enlarged forearms with long hairs and orange-and black markings:  M. pugnata (shown above), M. latimanus and M. frigida.

Females:  Three female leafcutters of New York -- the black and gray leafcutter, the blueberry leafcutter and (shown directly above), the small-handded leafcutter -- share distinctive traits that make them difficult to differentiate.  All three are robust black bees with predominantly black scopal hairs.  All three have pale hairs on the top portions of the first two segments of their abdomens (T-1 - T-2), and black on the remaining segments (3-6).  The sixth segments of their abdomens also bear stiff, black bristles.  All three species have four-toothed mandibles and dark eyes.

 

Females of these three species can be best told apart by minute differences in their mandibles. The three species also show these differences:  (1)  M. mucida and M. gemula females have dark hairs on the sides of their second abdominal segments (T-2); on M. mucida, the dark hairs form a larger patch than on M. gemula.  (2) M. melanophaea females often have bright orange scopal hairs on the second through fifth abdominal segments (S-2 - S-5).

A male Xanthosarus leafcutter (Megachile melanophaea or Megachile mucida)

All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography

A male Megachile melanophaea / mucida

A female Xanthosarus leafcutter, possibly M. mucida

Frigid leafcutters are eye-catching – females have bright orange scopal hairs, and males have enlarged, pale front legs fringed with flamboyant hairs and decorated with orange and black markings.  These bees have the hefty build characteristic of members of the subgenus Xanthosarus.  In addition to being large, female frigid leafcutters are loud buzzers, and this, combined with their size, makes them especially conspicuous as they fly around a field.

Frigid leafcutters appear in Rockefeller State Park Preserve in early July.  The bee shown here was found near a woodland, on the edge of a preserve parking lot covered with hardscrabble weeds such as crown vetch and bird’s foot trefoil.

Frigid leafcutters are broad generalist pollinators.  In our area, they are seen most often visiting members of the pea family (such as clovers, vetch and bird’s foot trefoil); and  members of the aster family such as thistles and black-eyed Susans.  These bees also pollinate smooth sumac and sarsaparilla.

Identification Information:  The female frigid leafcutter is a robust  bee with striking orange scopal hairs under its abdomen.  The female shown here measures nearly 3/5”, and its abdomen is broad and shovel-shaped.  To the naked eye, the female frigid leafcutter appears black, with thick pale hairs around its antennae and lower face; a mane of pale thorax hairs; dense pale hairs on its first two abdominal segments; and stripes of pale hair banding the third through fifth abdominal segments.  

 

Under magnification, other distinctive traits of this bee emerge:  the hairs on the top of the female frigid leafcutter's head are dark; the bee’s thorax hairs are both light and dark; and long dark hairs sprout from the top of the bee's abdomen, between the pale bands.  As shown in the photo strip at right, the bee’s last abdominal segment (T-6) is covered on top with dark hairs, a trait that helps distinguish it from other local leafcutter species with orange scopal hairs. The underside of the sixth segment (S-6) is covered in bright orange hairs.

Examination under magnification is sometimes necessary to identify female frigid leafcutters, because the bees’ yellow scopae make them superficially resemble flat-tailed leafcutters, which are far more abundant in the preserve.  Flat-tailed leafcutters (shown directly below on this guide page) are smaller and their thoraxes lack the bushy appearance of frigid leafcutter thoraxes.  Under magnification, the two bee species differ substantially:  flat-tailed leafcutters lack erect black hairs on their sixth abdominal segment (T-6), and their four-toothed jaws are different.  The inner (uppermost) tooth of the female rigid leafcutter’s jaw is described as “broadly truncate” -- it has a nearly square upper corner and a long, straight side.  This minute trait is the surest way to distinguish the female frigid leafcutter bee from similar species.

Male frigid leafcutter bees resemble the male Xanthosarus leafcutter shown in the guide entry immediately preceding this one. The male frigid leafcutter’s front legs are broadly expanded like that of the Xanthosarus male bee shown above.  Distinguishing characteristics of male frigid leafcutters include the following.  (1) On male frigid leafcutter bees, the expanded front legs are yellowish-white with two brown bars on the front end of the front femur.  (2) The forelegs terminate in tarsi (feet) that are black -- a trait that helps distinguish them from the similar species Megachile latimanus, whose males have pale front tarsi.  (3)  Male frigid leafcutters also have a concave ridge just below and behind the wing base, described in the Discover Life Database as “scoop-like” toward the top, with a glassy yellowish rim.  (4) Males, like frigid leafcutter females, have four-toothed jaws.

Frigid Leafcutter Bee

Megachile frigida
(Subgenus Xanthosarus)

Females:  1/2” to 3/5”   -   Males:  2/5” to 3/5

All photos (c) 2014 - 2017 Sharp-Eatman Nature Photography

A female frigid leafcutter

Silver-tailed Petal-cutter Bee

Megachile montivaga 
(Subgenus Megachile)

females:  2/5" to 1/2" (medium-sized)

males:   1/3" to 2/5" (medium-small)

Megachile montivaga is a rarely seen leafcutter bee whose Latin name translates to the mysterious and enticing "mountain-wanderer".  In English, however, this bee's common name is "silver-tailed petal-cutter". 

 

This pretty bee belongs to the subgenus Megachile.  Leafcutters of this subgenus vary fairly widely in behavior and physical shape.  Silver-tailed petal-cutter bees in particular have slender abdomens and carry the distinction of using flowers rather than leaves to line the walls of their tunnels.  According to a 1985 study by entomologists Sheffield, Ratti, Packer and Griswold, this trait is unique among leafcutters of the Megachile subgenus. 

 

Silver-tailed petal-cutters usually construct nests in the ground, but they also build them in the hollowed-out piths of old stems. Wilson and Carril, authors of The Bees in Your Backyard, report that Megachile montivaga bees prefer using the petals of clarkia flowers over all others to line their nests.  The bee shown at right was found cutting the petals of evening primrose (Oenothera), a flower which is in the same plant family (Onagraceae) as clarkia.   (Evening primrose, a native to the prairie states, occasionally appears as an escaped garden plant in the pastures of the park's Rockwood Hall.)  Both flowers have the common trait of possessing petals that are thin and delicate with a wide surface -- good for furnishing easy-to-trim, large pieces with which to wrap tunnels.

Silver-tailed petal-cutters are generalist pollinators. They have been recorded foraging on an extensive array of plants, among them clarkia, milkweed, asters, centaurea, thistles, fleabane, blanket flowers, sunflowers, birds-foot trefoil, rabbit pea, geranium, chokeberries and roses.

Identification information:  The female silver-tailed petal-cutter shown here is a half-inch black bee with a long, parallel-sided abdomen striped with five bands of white hair. The female bee has pale hairs on the sides of its face and around its antennae; sparse pale hairs on its thorax; and long, white scopal hairs under its abdomen. Despite this bee's name, the tail-end segment of the female bee's abdomen is black -- although its white scopal hairs may flash from beneath the bee's underside as it flies, giving it a "silver-tailed" look.

 

A distinguishing trait of female bees of this species is that they have five-toothed jaws that lack cutting blades. (The females of most of the other species on this guide page have jaws with cutting edges).  In addition, the tip of the female bee's abdomen is upturned  and convex. These traits are shown in the photo strip at right.

The male silver-tailed petal-cutter is slightly smaller than the female (as small as 1/3").  The male is a black bee with fairly bushy white hairs on its face and front legs. Its front feet (tarsi) are dark.  The male bee has three teeth on each jaw rather than five like the female bee.  The middle of the male bee's sixth  abdominal segment protrudes noticeably.

A Female Silver-tailed Petal-cutter Bee on Evening Primrose

All photos (c) 2014 - 2017 Sharp-Eatman Nature Photography

Relative Leafcutter Bee

Megachile relativa
(Subgenus Megachile)

females:  1/3” – 1/2” (medium-sized)

males:   3/10” – 2/5” (small to medium-sized)

Megachile relativa is a striking bee; females have electric orange scopal hairs under their abdomens.  Relative leafcutters have been sighted only a few times in Rockefeller State Park Preserve, visiting the sunny edges of open land bordering woods, where the bees feed on clover, bird's-foot trefoil and vetch.

 

The relative leafcutter is a generalist pollinator that has been documented frequenting an array of plants, among them pea family members (such as trefoil, clover and vetch); hard-bitten weedy plants of disturbed land such as viper’s bugloss, winter cress, ragwort and field mustard; members of the aster family such as fleabane, black-eyed Susans, cornflowers, chrysanthemums, sunflowers, goldenrod, gumweed and ox-eye daisy; and commercial crops such as blueberries and caneberries.  Studies done in Saskatchewan have shown Megachile relativa to be common in commercial crop fields.

 

Megachile relativa leafcutters prefer nesting along the edges of woodlands in the hollowed-out stems of pithy plants such as sumac.  The female bees line their tunnels with oblong leaf pieces and plug the entrances of each tunnel chamber with round pieces, habits common to many leafcutter species.

 

Relative leafcutters may produce more than one generation per year.  The first generation hatches in mid-summer, around the first week of July in our area. The bee larvae take about 16-18 days to mature and emerge.  A second generation may then overwinter and surface in early summer the following year.  Males tend to emerge first from chambers closest to the tunnel openings, while females tend to surface later, from chambers located deeper in the tunnels. (Such behavior is typical of many leafcutter species.)

 

The nests of relative leafcutter bees are preyed on by the stunning Porter’s cuckoo leafcutter bee, shown farther down on this page.  Porter’s cuckoos invade relative leafcutter nests and deposit eggs in them.  When the cuckoo larvae hatch, they kill off the leafcutter eggs or young and devour the pollen stores left for them by the mother leafcutter bees.  Canadian studies have shown that Megachile relativa are also preyed on by parasitic wasps and other species of cuckoo leafcutters, including Coelioxys funeraria and C. moesta.

We recommend Stephen Humphrey's video of a female Megachile relativa constructing its nest. 

 

Identification information:  The female bee shown here is a medium-sized leafcutter, with a black abdomen banded by stripes of pale hairs and fringed underneath with bright yellow-orange scopal hairs.  Female relative leafcutters’ orange scopal hairs set them apart from most other leafcutters found in the park, because this trait is shared by only a few park species (such as the frigid and flat-tailed leafcutters, shown below).  

Female relative leafcutters are best identified through the use of a macro lens or strong magnifying glass --because female bees bear the distinctive trait of having five teeth on each jaw.  This trait helps differentiate them from the vast majority of other New York leafcutter species. Only four other New York leafcutters species include females with five-toothed jaws (Megachile centuncularis, M. inermis, M. ingenua and M. latimanus).  Female relative leafcutters can be further distinguished by the presence on their five-toothed jaws of a cutting edge between the second and third tooth  -- as shown in the photo strip at right.

 

Similar species:  There are a handful of leafcutter species in the Northeast (not yet found in the park) whose females have orange scopal hairs – of these, the leafcutters Megachile centuncularis and M. lapponica are most often confused with relative leafcutters.  M. centuncularis can be distinguished by the fact that it has black hairs on the top of its last abdominal segment (T-6); M. lapponica has black scopal hairs on the underside of the same segment (S-6).  On relative leafcutters, the hairs on the top and the underside of the sixth segment are yellow orange -- so that, to the naked eye, the tip of the bee's abdomen seems to flash like an orange flame.  (Nonetheless, it is notable that these golden-orange abdomen-tip hairs  may become worn down and  difficult to perceive on older specimens).

 

​Males:  Male relative leafcutters are slightly smaller than the females.  Males have black bodies banded with stripes of pale hair; dense white hairs around their antennae; three-toothed jaws; and a clypeus (the face part just above the jaws) that bears a prominent median tubercle on its middle bottom edge.  Male relative leafcutters can be difficult to distinguish from males of many similar species – they closely resemble males of the species Megachile lapponica.  The best way to identify a male Megachile relativa is to observe one mating with a female, since females are easier to identify. 

A female Megachile relativa

A female Megachile relativa

All photos (c) 2014 - 2017 Sharp-Eatman Nature Photography

Flat-tailed Leafcutter Bee
Megachile mendica
(Subgenus Litomegachile)

females 2/5-1/2"; males 3/10"-2/5" (medium-sized)

Subgenus Litomegachile. The flat-tailed leafcutter belongs to the subgenus Litomegachile.  Leafcutters in this subgenus have broader builds than those belonging to the subgenus Sayapis, shown at the top of this guide page, but lack the robust builds of the subgenus Xanthosarus leafcutters shown immediately above.  Litomegachile leafcutters of New York have proportionately short, somewhat wide bodies; dark heads; dark thoraxes partly covered with pale hairs; and dark abdomens striped with pale bands.  They are roughly honey-bee size or smaller.  Male and female bees have dark green eyes.  Females have four teeth on each jaw, and males have three.

 

Three species comprise the Litomegachile subgenus in New York:  the flat-tailed leafcutter bee (Megachile mendica); the common little leafcutter bee (Megachile brevis); and the Texas leafcutter bee (Megachile texana).  These three species -- particularly the males -- may be difficult  to tell apart without the aid of an expert.  They vary slightly in size:  Megachile texana  is the largest (roughly between 2/5" and 1/2").  M. mendica is somewhat smaller (females are 2/5"-1/2"; males are 3/10" - 2/5").  M. brevis is the smallest (females are 1/3" - 1/2"; males are 1/4-1/3").  In all three species, females tend to run larger than males.

​All three of these New York Litomegachile share certain behavioral traits.  All are generalist pollinators.  All three are fairly noisy bees; they stand out in a garden because they buzz loudly as they fly between flowers and and stop pollinate.  All three species can be observed frequently striking a characteristic leafcutter pose, flexing the ends of their abdomens backwards into the air.  And all three are generalist pollinators.

Although these three species are found in southern New York, only flat-tailed leafcutters (M. mendica) have been formally documented and photographed in Rockefeller State Park Preserve and Stone Barns Center for Agriculture.  We have chosen, however, to show all three kinds of leafcutters here, as an aid to distinguishing among Litomegachile species.  Texas leafcutters and common little leafcutters are shown in the guide entries immediately below.

Flat-tailed Leafcutters.  Flat-tailed leafcutters are hard to miss:  they buzz loudly when flying and foraging for pollen.  Once inside flowers, females tend to whirl around , vibrating energetically.  This method of shaking pollen loose makes flat-tailed leafcutters particularly efficient pollinators of many legumes.

Flat-tailed leafcutter bees appear in the park and Stone Barns in mid-June and remain throughout the summer, pollinating a variety of wildflowers, among them mountain mint, goldenrod, asters, wild roses, ironweed, thistles and milkweed.  The bees shown here were feeding on strawflowers, mountain mint and ironweed.

Female flat-tailed leafcutters often can been seen flying low over the ground in a characteristic zig-zagging pattern. They do this in order to find cavities in hollow stems and sticks to use as nesting places.  

 

The female flat-tailed leafcutter constructs its nest in a distinctive form, as a series of chambers.  Eggs for female offspring, which take longer to develop, are stored in the innermost and most protected chambers, while eggs for males are kept closer to the nest entrance.  

Flat-tailed leafcutters are sometimes preyed upon by Say's cuckoo leafcutters (shown below).

 

Identification Information:  Female Megachile mendica are perhaps the easiest to identify of the three Litomegachile species found in our area.  Even seen from a distance, female flat-tailed leafcutters are striking, because they have bright yellow or orangish-yellow scopal hairs.  (Both M. mendica and M. texana, shown below, have predominantly white scopal hiars.) The tip of the female flat-tailed leafcutter bee's abdomen also has a distinctive flat profile, rather than the concave dip typical of many leafcutters (as shown in the photo strip at right).

 

Both male and female flat-tailed leafcutters have dark bodies banded by bands of pale hairs.  Both have green eyes.  Males have dense pale hairs covering their faces.

Viewed more minutely:  The abdominal tip (T-6) of the female flat-tailed leafcutter lacks a notch and is dark; it does not have pale hairs on it. The bee's scopal hairs carried under its abdomen are yellow-orange on the first five segments; the sixth segment (S-6) is mostly yellow with black hairs at the tip. 

As shown in the photo strip at right, the final abdominal segment on a male flat-tailed leafcutter's abdomen is notched and partly covered with pale hairs.  The male bee's fifth abdominal segment (T-5) lacks a hair band.  These minute traits help distinguish it from the very similar leafcutter species Megachile brevisAccording Bugguide.net, male M. brevis and M. mendica can

be impossible to tell apart with the naked eye.

A female flat-tailed leafcutter bee with orange scopal hairs under her abdomen

A male flat-tailed leafcutter bee

All photos (c) 2014 - 2016 Sharp-Eatman Nature Photography

Texas Leafcutter Bee*
Megachile Texana (Subgenus Litomegachile)
2/5 - 1/2" (medium-sized)
* not yet documented within RSPP

As noted above, Texas leafcutter bees have not yet been documented as residing in Rockefeller State Park Preserve or Stone Barns.  We are furnishing a guide entry on Megachile texana, because there have been informal sightings of Texas leafcutter bees in fields bordering the park.  Our hope is that the inclusion of this species here will lead to its future documentation within the preserve.  In addition, this entry may serve as an aid in distinguishing and identifying members of the leafcutter subgenus Litomegachile.

Texas leafcutters were first described in 1878 by the entomologist Cresson.  Megachile texana bees are found throughout the United States, as far west as California, as far south as Texas and Florida, and as far North as New England. 

 

Texas leafcutter bees emerge in spring in southern New York and remain visible in our general area through September.  These bees are known pollinators of cranberries and rhododendrons.  They are also unusually broad generalists that feed on more than 80 species of plants. In our general region, Texas leafcutters are frequently found foraging on milkweeds, clover, thistles and other aster-family members.  The bee shown here was feeding on purple salvia.

Megachile texana leafcutters build solitary nests in the ground, often hidden under rocks or objects. They sometimes re-use nests abandoned by other insects. They also dig their own nests:  in a 1981 study on leafcutters, entomologists Eickwort, Matthews and Carpenter observed Texas leafcutter females excavating their own nests under rocks in an open field.  The bees dug shallow tunnels in which to lay eggs, dividing the tunnels into individual chambers that each held one egg. Female Texas leafcutters sometimes can be seen backing out of their burrows, dragging sand with their mandibles and forelegs, in order to dig out tunnels.

 

Identification Information:  Both male and female Texas leafcutters are dark bees with green eyes and abdomens banded with pale hairs.  Female Texas leafcutter bees have remarkably long, bright-white scopal hairs which, according the the Discover Life database, make them "appear to have a bit of cotton stuck underneath" their abdomens. This trait aids greatly in telling the bees apart from the other leafcutters.

Generally, female Texas leafcutters have pale hairbands striping the first five segments of their upper abdomens. The scopal hairs beneath the female bees' abdomens are white under the first five segments and dark under the sixth segment. In profile, the tip of the female bee's abdomen has a concave curve.

More minute traits that help distinguish female Texas leafcutters from other New York Litomegachile leafcutter species include the following:  (1) the female Texas leafcutter has black bristles on the sides of the second through sixth segments of its abdomen.  (2)  the female Texas leafcutter has a line of white hairs on its thorax, where the scutum and scutellum meet (shown in the photo strip at right).

M. texana males are much harder to differentiate from other Litomegachile males. Distinctions between male M. mendica and M. texana are very subtle:  one difference is that the rims of the fifth abdominal segments of M. texana have white hairs while those of male M. mendica do not.    An imageshowing this trait is available at this DIscover Life page.  Male M. texana also have conspicuous dark hairs intermixed with the light hairs on thier thoraxes; and dark feet (tarsi).

Common Little Leafcutter Bee*
Megachile brevis (Subgenus Litomegachile)
1/4 "- 1/2" (medium-sized)
*not yet documented within RSPP

Megachile brevis, known as the common little leafcutter bee,  is in fact one of the most common leafcutter species in North America; it is found from coast to  coast, from Florida through Canada.  Like the Texas leafcutter shown above, Megachile brevis has not yet been formally documented in the preserve or in neighboring Stone Barns. These leafcutters are, however, found in the immediate area.  As noted above, they have been included in this guide to aid in the identification of leafcutters in the subgenus Litomegachile.  Please contact this guide's authors if  you think you have observed this species in the preserve.

Like other typical members of their subgenus, Megachile brevis leafcutters are solitary bees.  According to entomologist Charles D. Michener’s The Social Biology of the Bees, while most solitary bees produce only one generation annually, common little leafcutters produce a succession of generations each year, so that , except in spring, all life stages of the bee, including larvae and pupae, can be found at any time during warmer months.

 

The Discover Life database records common little leafcutters as feeding on a broad range of flowers, including asters, yarrow, clover and caneberries. Michener wrote, in The Bees of the World,  that common little leafcutters collect pollen from whitish, blue, purple and pink flowers of various families, but rarely collect from yellow Asteraceae-family flowers such as sunflowers.  (The female bee shown at right, found 30 miles north of the park, was feeding on purple hyssop.)  

 

Identification Information.  M. brevis, like the two Litomegachile leafcutters shown above, is a black bee with white bands of hair on its abdomen.  M. brevis is a notably small leafcutter -- its Latin name, brevis, means "small" or "short".  Both female and male common little leafcutters tend to run smaller than their M. mendica and M. texana counterparts .

 

Female common little leafcutters have white scopal hairs. This trait distinguishes them from M. mendica females, which usually have orange-yellow scopal hairs.  M. texana females have black scopal hairs under the sixth segments of their abdomens, while common little leafuctters have white hairs on S-6.   In addition, the hair bands on the sides of the common little leafcutter's abdomen are white on segments T-2 through T-5; on M. texana, dark bristles intermingle with pale hairs.

 

M. brevis males are harder to identify.  In 1987, the entomologist Robertson commented in North American Bees that M. brevis and M. mendica closely resemble one another.  Robertson wrote that one minute trait of male common little leafcutters helped tell them apart:  the hind edge of the  6th abdominal segment of a male M. brevis has “two median teeth like those of a circular saw”. 

The most useful guide on the web for distinguishing M. brevis, M. texana from M. mendica males can be found in the Litomegachile key  of the University of Florida's entomology Department.

Texas leafcutter bee - Megachile texana - (c) Copyright 2017 Paula Sharp

A Texas leafcutter bee (female)

All photos (c) 2014 - 2017 Sharp-Eatman Nature Photography

A common little leafcutter bee (female) 

All photos (c) 2014 - 2017 Sharp-Eatman Nature Photography

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Alfalfa Leafcutter Bee
Megachile rotundata
(Subgenus Eutricharaea)

1/4" - 1/3" (medium-small)

Perhaps the best known leafcutter bee is the miniscule alfalfa leafcutter.  This European bee was introduced accidentally into America shortly after World War II, and is now widely used to pollinate a range of crops including blueberries, legumes and root vegetables. According to the U.S. Department of Agriculture, alfalfa leafcutter bees -- which usually run no more than 1/4" to 1/3" in size -- are exceptional pollinators of greenhouse carrots; the USDA has estimated that 150 alfalfa leafcutter bees can pollinate greenhouse carrots as efficiently as 3,000 domesticated honey bees.  

 

Charles D. Michener notes that female alfalfa leafcutters are also prolific; in a life lasting a mere seven weeks or less, a single female alfalfa leafcutter bee can produce 77 offspring.  Alfalfa leafcutter bees can now be purchased in lots that arrive through the mail, packaged in cartons, ready to be released in fields and greenhouses.

 

The bees tend to make repeated trips to the same plant. They are  fidgety foragers that alight only briefly on flowers before abruptly flying off.  Alfalfa leafcutters can be found foraging on goldenrod, asters, mountain mint, carrots and onions in the gardens at Stone Barns Center for Food and Agriculture.  These bees are comically energetic pollinators, entertaining to watch.  The picture at right shows an alfalfa leafcutter bee standing on her head in an effort to extract nectar and pollen from an onion flower.

 

Identification information:  Alfalfa leafcutters belong to the subgenus Eutricharaea, a bee group also known as "small leafcutter bees".  In the United States and Canada, this subgenus is represented by three very similar non-native species, all originating from Europe:  the alfalfa leafcutter (Megachile rotundata); the apical leafcutter (Megachile apicalis); and the elegant leafcutter (Megachile concinna). Differentiating among these three species with the naked eye is difficult, and often impossible in the case of male bees.

The bee at top right is a female alfalfa leafcutter. This bee is about 1/3" long.  She has a stout black body banded by stripes of pale hair; long white scopal hairs on her abdomen's underside, used to carry pollen; greenish eyes; and white hair on her face along the inner edge of her compound eyes. The last segment of the female bee's abdomen is black and unnotched. 

 

Male alfalfa leafcutters have the same general appearance as the females, but are somewhat smaller and  lack the long white scopal hairs.  Instead, the striped pattern on the tops of male alfalfa leafcutters' abdomens continues onto the undersides of the bees (as shown in the photo strip at right),.  This is an identifying  trait of male leafcutters of the Eutricharaea subgenus.

A female alfalfa leafcutter bee on standing on her head,  on an onion blossom

A female alfalfa leafcutter bee 

All photos (c) 2014 - 2017 Sharp-Eatman Nature Photography

Cuckoo Leafcutter Bees

Cuckoo leafcutters prey on leafcutter bees by invading their nests and depositing eggs in them.  When the cuckoo's young hatch, they eat the hosts' eggs and then devour the stores of nectar and pollen left by the mother leafcutter for her offspring.  When such attacks occur late in the season, cuckoo larvae may spin cocoon-like structures inside of their hosts' nests and overwinter in them.

 

Many cuckoo bees of other types -- for example, Triepeolus  bees (which prey on long-horned bees) and nomad bees (which generally prey on Andrena mining bees) -- are not closely related to the bees they parasitize.  Such cuckoos are shown on the cuckoo bee page of our guide.  We have chosen to feature leafcutter cuckoos here, however, because they belong to the same group as their leafcutter prey -- the tribe Megachilini -- and somewhat resemble them.  Within that tribe, leafcutter cuckoos comprise a genus called Coelioxys. 

 

The Greek Coelioxys means "sharp belly," a genus name that refers to the tapered, pointed abdomens of cuckoo leafcutters.  As shown at right, female Coelioxys have spade-shaped abdominal tips that allow the cuckoos to break through the brood-cell walls that leafcutters construct with leaves, petals and other materials.  Male cuckoo leafcutters have abodmens armed with multi-pronged tips.

According to Charles D. Michener, members of the genus Coelioxys share the distinctive trait of having hairs on their eyes.  In addition, the wings of the cuckoo leafcutter bee have only two submarginal cells, and the back rim of the bee's scutellum (at the hind end of the thorax) is often toothed.  (These traits are shown in the photo strip at right.)

Both female and male cuckoo leafcutters sip nectar from flowers.  Females do not gather pollen or transport it under their abdomens as is customary of leafcutters. This is because female cuckoos acquire pollen by robbing it from  their hosts' nests. Thus, female cuckoo leafcutters also lack the long abdominal pollen-collecting hairs characteristic of leafcutter bee females.

Cuckoo leafcutters often can be seen lifting their pointed, conical abdomens, in a scorpion-like manner.  Both males and females also have a habit of grasping leaves and stems with their jaws:  cuckoo leafcutters sometimes can be found sleeping on vegetation, hanging upside-up or upside-down by their mandibles. 

Most individual Coelioxys species target specific species of leafcutters.  Thus, for example, Coelioyxs porterae cuckoos parasitize the nests of relative leafcutters, while Coelioyxs sayi invade the nests of flat-tailed leafcutters.  In other regions, cuckoo leafcutters exist that target bees other than leafcutters.

There are seven subgenera (subgenuses) of cuckoo leafcutter bees in New York State.  Six species representing four subgenera have been found in the preserve.  These are shown below.

General Identification Information:  Cuckoo leafcutter species appear very similar to the casual observer, and species identification is often best left to an expert.  Cuckoo leafcutter species are told apart by such traits as leg color; the patterns of pale hair bands and grooves on the abdomen; the form of the abdominal tip; and the shape of the bottom edge of the cuckoo's  thorax.  Male leafcutter cuckoos often have foveae (depressions) on the sides of their second or third abdominal segments (T-2 and T-3). Noting the size, shape and presence or absence of such foveae often aids in species identification.

Cuckoo Leafcutter Bees  (Genus Coelioxys)

1/4" - 1/2"  (small to medium-sized)

Above left :   A  male Say's cuckoo leafcutter bee resting upside-down
Above right:   The pointed abdominal tip of a female cuckoo leafcutter
Below right:  The multi-pronged abdominal tip of a male cuckoo leafcutter
Below:   A female modest cuckoo leafcutter gripping a stem with her jaws 

A female Porter's cuckoo leafcutter

CUCKOO LEAFCUTTERS
of the Subgenus Cyrtocoelioxys 

Modest Cuckoo Leafcutter

Coelioxys  modestus

1/4" - more than 1/2" (small to medium-sized)

Modest cuckoo leafcutters (Coelioxys modestus)  belong to the subgenus Cyrtocoelioxys.  They are cleptoparasites of the belted leafcutter (Megachile centuncularis) and of the resin bee species Megachile campanulae wilmingtoni (a variation of the bellflower resin bee, found in coastal areas of the southeastern United States). Although neither of these host  bees has been documented in the preserve, it is likely that some belted leafcutters reside there, as this species is relatively common in the general New York area.

 

The two bees shown here illustrate the considerable size range of these bees.  The smaller one barely measured 1/3", while the larger one was nearly 3/5".

 

The small modest cuckoo leafcutter at right was found foraging on goldenrod during early September 2017.  The second, larger cuckoo (shown in the photo strip at right )was found outside the preserve -- in a public garden located in Riverdale, New York, 25 miles to the south of the preserve.  This bee was feeding on sneezewort in early August, 2017.

​Modest cuckoo leafcutters have been documented feeding on such plants as sunflowers, asters, ceanothus, sweet clover, sumac, verbena, bellflowers and mountain mint. 

​Identification information:  Modest cuckoo leafcutters have dark red legs or red-and-black legs; black heads and thoraxes; and black abdomens banded by pale hairs. The last segment of the female bee's abdomen is distinctive, as shown in the photo strip at right.  Female and male bees have dark brownish-green eyes.

 

​As noted, modest cuckoo leafcutters range greatly in size -- from just over 1/4 " to more than 1/2" inch long. Few leafcutters in our area run so small, and thus the bees' modest size aids in their identification.  The reverse is also true -- few cuckoo leafcutters in our area reach the 3/5" length of the second female bee shown here in the photo strip.

Three minute traits help identify females of this species:  (1) when viewed from the side, the upper half of the sixth segment (T-6) of the female bee's abdomen is upturned; (2) the lower half of the last segment (S-6) of the female bee's abdomen sports a fringe of hair; and (3) the first segment of the female bee's abdomen is edged with pale hairs along its front ridge. Male modest cuckoo leafcutters have multi-pronged abdominal tips.

TAXONOMY  -  MODEST LEAFCUTTER

Family:  Megachilidae

Subfamily:  Megachilinae

Tribe:  Megachilini

Genus:  Coelioxys

Subgenus:  Cyrtocoelioxys

Species:  Coelioxys modestus

A female immaculate cuckoo leafcutter

CUCKOO LEAFCUTTERS

of the Subgenus Synocoelioxys

Synocoelioxys leafcutter.  The male cuckoo leafcutter at right belongs to the subgenus Synocoelioxys.  Synocoelioxys cuckoos prey specifically on leafcutters of the subgenus Sayapis -- such as the frugal, pugnacious and hostile leafcutters featured near the top of this page. 

 

Cuckoos of this subgenus are documented frequenters of sunflowers, cornflowers, black-eyed Susans and spurge.  The bee shown here is feeding on rudbeckia. 

 

​Identification information:  These bees have black heads and thoraxes; and black abdomens encircled by white bands.  Their legs are reddish-brown and their eyes dark olive-green. A distinguishing trait of this subgenus is that the white bands on the bees' abdomens are interrupted in the middle.

TAXONOMY  - SYNOCOELIOXYS CUCKOO LEAFCUTTER

Family:  Megachilidae

Subfamily:  Megachilinae

Tribe:  Megachilini

Genus:  Coelioxys

Subgenus:  Synocoelioxys

Right:  A male
cuckoo leafcutter
of the subgenus 
Synocoelioxys

Northern Cuckoo Leafcutters
of the subgenus Boreocoelioxys

 

Porter's Cuckoo Leafcutter

Coelioxys porterae
1/3" - 1/2" (medium-sized)

Say's Cuckoo Leafcutter

Coelioxys sayi
1/3" - 1/2" (medium-sized)

Eight-Toothed Cuckoo Leafcutter
Coelioxys octodentatus

3/10" - 1/2" (small to medium-sized)

Coelioxys bees of the subgenus Boreocoelioxys are known as northern cuckoo leafcutter bees.  The vast number of cuckoo leafcutters found in Rockefeller State Park Preserve belong to this subgenus.  The park's northern cuckoo leafcutters are represented by at least three species:  Porter's cuckoo leafcutter; Say's cuckoo leafcutter; and the eight-toothed cuckoo leafcutter.

Porter's cuckoo leafcutters.  According to entomologist J.R. Baker's voluminous 1975 treatise, Taxonomy of Five Nearctic Subgenera of Coelioxys, Porter's cuckoo leafcutters invade the nests of relative land frigid leafcutters.  (Both of these species are shown higher up on this guide page.)

 

Porter's cuckoo leafcutters feed on such plants as geraniums, false indigo, hydrangea, cranberries, blueberries, goldenrod and asters.   The Porter's cuckoo leafcutters featured here were found drinking nectar from coreopsis and butterfly weed in the park's Visitor Center garden in late June and early July of 2017. These bees are relatively uncommon in the park.

 

Say's cuckoo leafcutters are the most common Coelioxys bees found in the park.  These cuckoos target the nests of flat-tailed leafcutter bees (shown higher up on this page).  Sometimes, after the cuckoo's eggs have been deposited in the flat-tailed leafcutter brood cells, the newly hatched cuckoos coexist with their prey, sharing the provisions left by the mother flat-tailed leafcutter.  Field studies have documented Say's cuckoo leafcutters and flat-tailed leafcutters emerging from the same nest.  

 

Say's cuckoo leafcutters drink nectar from a very wide array of flowering plants, among them, blackberries, melons, squash and sunflowers.  The Say's cuckoos shown here were found feeding in the park in July and August on orange butterfly weed, mountain mint and goldenrod. 

Eight-toothed cuckoo leafcutters, like Says' cuckoo leafcuttters, infiltrate the nests of flat-tailed leafcutter bees.  Eight-toothed cuckoo leafcutters also have been documented parasitizing the nests of at least four other leafcutter species:  the common little leafcutter  (Megachile brevis), the Texas leafcutter (Megachile texana), the alfalfa leafcutter (Megachile rotundata) -- all of which are shown above on this guide page --  and the belted leafcutter (Megachile centucularis).  

 

Eight-toothed leafcutters forage on a broad range of wildflowers and native plants, among them elderberry, sumac, wild asters, onions and Virginia creeper.  The male bee shown here was feeding on goldenrod on a sunny park trail in early September.

​Identification information:   All three of these northern cuckoo leafcutter species have dark abdomens banded by stripes of short pale hairs; thoraxes with teeth located on either side of the hind edge of the scutellum; red, black or red-and-black legs; and green eyes.  Females of these species have pointed, conical abdomens with spearlike tips.  Males have impressive abdominal tips terminating in multiple prongs.  Male Boreocoelioxys bees found in our area lack foveae (depressions) on the sides of their third abdominal segments.

Porter's cuckoo leafcutters are striking, long-bodied bees. They have all-black legs, a trait that makes them readily distinguishable from Say's and eight-toothed leafcutters. Other traits of Porter's leafcutters, visible only on minute inspection, include the following:  (1) females have distinctive abdominal tips with tooth-like notches near the ends; (2) and they sport relatively long hairs on their eyes.  (3) The male C. porterae also has an unusually-shaped abdomen, with prominent depressions on the first segment (T-1),; and an unpitted line dividing the fourth and fifth segments [T-4 and T-5)  (These traits are shown in the first photo strip at right.)

Say's and eight-toothed cuckoo leafcutters have predominantly red legs and dark wings.  The bees' tegulae (located where the wing joins the bee's body) are red. Both Say's and eight-toothed cuckoo leafcutter males have deep grooves that traverse the second and third segments of their abdomens (T-2 and T-3). On Say's leafcutters, these grooves may be interrupted in the middle.

These two species differ subtly (as shown in the second photo strip at right):  (1) The female Say's cuckoo leafcutter has a distinctive clypeus (the face part above the jaws)  with a shallow U-shaped lower rim.  On female eight-toothed leafcutters, the lower rim of the clypeus runs straight across.  (2) Male and female Say's leafcutters have legs that are black near the base and reddish on the lower segments.  Eight-toothed leafcutters, by contrast, usually have entirely red (or mostly red) legs.

 

TAXONOMY  -  PORTER'S LEAFCUTTER, SAY'S CUCKOO LEAFCUTTER, EIGHT-TOOTHED LEAFCUTTER

Family:  Megachilidae

Subfamily:  Megachilinae

Tribe:  Megachilini

Genus:  Coelioxys

Subgenus:  Boreocoelioxys

Species:  Coelioxys sayi, Coelioxys octodentata
   and  Coelioxys octodentatus

A female Say's leafcutter gripping a mountain mint leaf with her jaws.

A male eight-toothed cuckoo leafcutter raising its abdomen tip in the air

CUCKOO LEAFCUTTERS
of the Subgenus Coelioxys

Immaculate Leafcutter

Coelioxys  immaculatus
1/3" - 1/2" (medium-sized)

Immaculate cuckoo leafcutters (Coelioxys immaculata)  belong to the redundantly-named subgenus Coelioxys.  These cuckoo leafcutters parasitize the nests of Megachile addenda leafcutters (shown higher up on this page).  

 

During late spring of 2017, a large Megachile addenda aggregation appeared in the Rockwood Hall section of the park.  Immaculate cuckoo leafcutters appeared in large numbers on the fringes of the aggregation.  The cuckoos would park themselves two or three feet from a given hole and engage in the following behavior.  

 

The cuckoos would wait, deathly still, blending almost completely into the dirt-and-crushed-pebble background of the nest area, watching the behavior of the female leafcutters. The female leafcutters would arrive at the nests periodically, bearing leaves to construct egg chambers one-by-one. Each time a targeted female leafcutter finished a chamber and emerged to fly off and gather more leaves and pollen, the immaculate cuckoo leafcutter watching the nest hole would sneak into  it like a burglar, presumably to pierce the outer wall of the newly-constructed egg chamber and to lay her own egg there. The cuckoo would then scamper from the hole a minute later and park again a few feet from the nest, awaiting the return of the female leafcutter bee.  This process would repeat itself throughout the day, assuring that the cuckoo bee had eggs in each of the individual nest chambers the leafcutter painstakingly provisioned for her own offspring.

Immaculate cuckoo leafcutters forage on such plants as blackberries, raspberries, milkweed and false indigo.  The bees shown here were found feeding on cow vetch and clover.

​Identification information:  Immaculate cuckoo leafcutters have red legs with dark top segments; black heads and thoraxes; and black abdomens encircled by white bands.  Females' faces are covered with short white hairs and bordered on the bottom of the clypeus (lower face) with a row of pale orange hairs. They have green eyes. A distinguishing trait of females of this species is the singular tip of the bee's abdomen -- shown in the photo strip at right.


 

TAXONOMY  -  IMMACULATE LEAFCUTTER

Family:  Megachilidae

Subfamily:  Megachilinae

Tribe:  Megachilini

Genus:  Coelioxys

Subgenus: Xerocoelioxys

Species:  Coelioxys immaculata

A female immaculate cuckoo leafcutter

An immaculate cuckoo leafcutter backing out of the hole of a Megachile addenda leafcutter

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REFERENCES:  For a comprehensive list of references used in compiling this guide, click here: 

 8-23-15