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Silver-tailed petalcutter


Genus Megachile

Genus Megachile  - Leafcutter Bees

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 here, 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 and covered with dark hairs; others are darkly-colored, with brown or pale hairs on their thoraxes or bands of hair on their abdomens.  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 of leafcutters containing more than 20 distinct species.  Nine species representing 5 genera have been found in Rockefeller State Park Preserve and Stone Barnes Center for Food and Agriculture.  They are shown below.

Alfalfa Leafcutter Bee
Leafcutter Bee Cutting Flower Petal - Megachiile - (c) 2016 Sharp-Eatman Photo

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

Subgenus Sayapis

Frugal Leafcutter Bee

Megachile frugalis

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

The 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 has a black head, body and legs; an abdomen banded with white hairs; and wings characterized as "smoky" in color.  Females have 4-toothed mandibles, and males have 3-toothed mandibles.  Males have an ostentatious fringe of long white hairs on their forelegs.


Long white scopae (pollen-collecting hairs) cover the female frugal leafcutter's sternum (the underside of the abdomen).  White hairs, intermixed with some dark hairs, also cover the female's face.  The female's clypeus (located on the lower part of the face) is black.  The presence of dark hairs on the female's clypeus is a distinctive trait that aids in identification of this species.


Frugal leafcutters are associated with prairie and arid habitats.  They range from the east to west coast of the United States, and occur as far north as New England and as far south as Costa Rica.  Megachile frugalis appears 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. 


Megachile frugalist is a documented pollinator 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. Frugal leafcutters also visit alfalfa and sunflower crops.


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.

Megachile frugailis

A female frugal leafcutter bee

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

Megachile pugnata

Pugnacious Leafcutter Bee

Megachile pugnata pugnata

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 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 leafcutters 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. 


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 female bees' abdomens are mostly white or pale yellow; they are dark on the sixth sternal segment (S6). The female pugnacious leafcutter 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 (the part of the head behind the eyes) of the female pugnacious leafcutter's head is unusually wide .

Both male and female pugnacious leafcutters have black heads, bodies, legs and tegulae (wing nodes).  Their abdomens are striped by well-defined bands of pale hairs. Males lack the proportionately huge mandibles of the females, however.  Males also have three-toothed mandibles, while female have five-toothed mandibles.


Male pugnacious leafcutters have distinctive forelegs:  as shown in the photographs here, the basitarsi of the males' are expanded, predominantly pale yellow, and adorned with long, yellowish-white hairs.

A female pugnacious  leafcutter bee

Pugnacious Leafcutter Bee

A male pugnacious leafcutter bee

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

Megachile inimica

A female  hostile leafcutter bee of the subspecies Megachile inimica sayi

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

Hostile Leafcutter Bee

Megachile inimica 
Subspecies Megachile inimica sayi

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 are fairly large for leafcutters -- usually between 2/5" and 3/5". These bees have long dark abdomens banded with pale hairs; dark thoraxes partly covered with pale hairs; and dark wings.  Females have pale scopal hairs under the first five segments of the abdomen (S1-S5), and dark hairs under the sixth (S6).

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.  Entomologist Karl Krombein wrote that he had observed hostile leafcutters forming cell partitions by combining circular leaf-cuttings with layers of sand and small pebbles.

Identification Information:  The faces of male hostile leafcutters are covered with white hairs.  Males have three-toothed mandibles and females four-toothed mandibles. Male hostile leafcutters have expanded forelegs, with the expanded portion (the bastarsi) mostly pale yellow (with some brown) and fringed with pale hairs.


As illustrated in the photo strip here, 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, the clypeus (the face part above the mandibles) comes to a low point in the middle of the bottom edge.  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 on Megachile inimical sayi and yellowish on Megachile inimica inimica.  In the subspecies Megachile inimica sayi, both males and females have primarily black legs, while  Megachile inimica inimica females have reddish legs.

Subgenus Xanthosarus

Cranberry Leafcutter Bee
Megachile addenda
(Subgenus Xanthosarus)
2/5" to 1/2" (medium-sized)

Unlike the three leafcuters featured above, Megachile addenda 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 are cranberry and blueberry poliinators and are associated with areas where these plants 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. 

Megachile addenda also feed on flowers in the legume family (Fabaceae), such as clover, false wild indigo, vetch and leadplant.  In the park, these bees can be 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, 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 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 are preyed on by immaculate cuckoo leafcutters (Coelioxys immaculata), which are shown on the next 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 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 predominantly bushy white scopal hairs; the last segment of the female bee’s abdomen (S6) is covered with 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 somewhat 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.

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

Megachile gemula

Small-handed Leafcutter Bee

Megachile gemula
(Subgenus Xanthosarus)

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

Like Megachile addenda 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 here, males have flamboyant white hairs on their forelegs.  Both males and females have 4-toothed mandibles.

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 base of the third segment (T-3).  The female bee's hind segments (T-4 - T-6) are black.  Pale hairs also partly cover the first four segments of the male bee's abdomen (T1-T4); 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 (T2) 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. mucida, 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.

Megachile addenda
Cranberry leafcutter bee

A male Megachile addenda leafcutter bee

A female Megachile addenda leafcutter bee

Cranberry Leafcutter

Black and Gray / Blueberry Leafcutter

Megachile melanophaea  / Megachile mucida

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

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 here. Male 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).  Black 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:  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 sternal  segments (S-2 - S-5).

 Leafcutter Bee - male Megachile (Xanthosarus) - (c) 2016 Sharp-Eatman photo

A male Xanthosarus leafcutter (Megachile melanophaea or Megachile mucida)

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

Female Xanthosaura LeCopyright 2016 Paula Sharpfcutter - (c) c

A male Megachile melanophaea / mucida

A female Xanthosarus leafcutter, possibly M. mucida

Frigid Leafcutter Bee

Megachile frigida
(Subgenus Xanthosarus)

Females:  1/2” to 3/5”, males:  2/5” to 3/5

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 Megachile frigida is a robust  bee with a black head, body and legs; a mane of dense thorax hairs; an abdomen with dense pale hairs on its first two segmentts (T1-T2) and pale narrow bands on its third through fifth segments (T3-T5); and a sternum covered with orange hairs.  The female shown here measures nearly 3/5”, and its abdomen is broad and shovel-shaped. 


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 surface of the bee's abdomen, between the pale tergal 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 frigid 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 leafcutters, 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 by entomologist C.S. Sheffield as “scoop-like” toward the top, with a glassy yellowish rim.  (4) Males have four-toothed mandibles.

Megachile frigida

A female frigid leafcutter

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

Subgenus Megachile

Silver-tailed Petal-cutter 

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, 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-cutters 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.  Megachile montivaga tend to use the petals of flowers in the family Onagraceae such as clarkia and evening primrose to line their nests.  Both of these flowers have petals that are thin and delicate with a wide surface -- good for furnishing easy-to-trim, large pieces with which to wrap tunnels.  (The authors have also seen these bees in Texas using Argemone, also called prickly poppy, for the same purpose:  this flower similarly has large, delicate petals. )  The bee shown here was found cutting the petals of evening primrose.  Evening primrose, or Oenothera, a native to the prairie states, occasionally appears as an escaped garden plant in the pastures of the park's Rockwood Hall. 

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 rear 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 here.

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.  There is a protrusion on the rear edge of the male's sixth  abdominal segment (T6) .  The male has 3-toothed mandibles.  

Megachile montivaga

A female Silver-tailed Petal-cutter on evening primrose

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

Relative Leafcutter Bee

Megachile relativa
s 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.


Relative 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.


Megachile relativa 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 leafcutters are preyed on by the stunning Porter’s cuckoo leafcutter bee, shown farther down on this page.  Porter’s cuckoo leafcutters 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.  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 two other known park species (the frigid and flat-tailed leafcutters).  

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 surface of its rearmost 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 pale hairs; dense white hairs around their antennae; three-toothed mandibles; and a clypeus (the face part just above the jaws) that bears a prominent median tubercle on its lower 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. 

Megachile relativa

A female Megachile relativa

Megachile relativa

A female Megachile relativa

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

Subgenus Litomegachile

Flat-tailed Leafcutter Bee
Megachile mendica
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 those in the subgenus Xanthosarus, shown immediately above.  Litomegachile of New York have proportionately short, somewhat wide bodies; dark heads; dark thoraxes partly covered with pale hairs; and dark abdomens banded with pale hairs.  They are roughly honey-bee size or smaller.  Males and females have dark green eyes.  Females have 4-toothed mandibles, and males have 3-toothed mandibles.


Three species comprise the Litomegachile subgenus in New York:  the flat-tailed leafcutter (Megachile mendica); the common little leafcutter (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").  Megachile mendica is somewhat smaller (females are 2/5"-1/2"; males are 3/10" - 2/5").  Megachile 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.

Although these three species are found in southern New York, only flat-tailed leafcutters (Megachiile mendica) have been documented in Rockefeller State Park Preserve and Stone Barns Center for Agriculture. 

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 leafcutters appear in the park and Stone Barns in mid-June and remain throughout the summer.  They are generalist pollinators that visit an array 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 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.   The nests of flat-tailed leafcutters are sometimes preyed upon by Say's cuckoo leafcutters (shownon the next guide page).


Identification Information:  Female Megachile mendica are 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 predominantly bright yellow or orangish-yellow scopal hairs. (Both Megachile mendica and M. texana have predominantly white scopal hiars.) The tip of the female flat-tailed leafcutter's abdomen also has a distinctive flat profile, rather than the concave tip typical of many leafcutters (as shown in the photo strip here).


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

As shown in the photo strip here, the tip of the 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 brevis

Megachile mendica

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

Flat-tailed leafcutter bee

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 at Rockefeller State Park Preserve or Stone Barns.  We are nonetheless 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.  

Texas leafcutters were first described in 1878 by the entomologist E. T. Cresson.  Megachile texana 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 leafcutters 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 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, entomologists Eickwort, Matthews and Carpenter observed Texas leafcutter females excavating their own nests under rocks in an open field.  The bees dug shallow tunnels and divided them 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 excavate tunnels.


Identification Information:  Both male and female Texas leafcutters are dark bees with green eyes and abdomens banded with pale hairs.  Female Texas leafcutters have remarkably long, bright-white scopal hairs which, according to entomologist C. S. Sheffield, 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 in the field.

Generally, female Texas leafcutters have pale hairbands on the first five abdominal segments (T1-T5).  The scopal hairs beneath the female bees' abdomens are white under the first five segments (S1-S5), and dark under the sixth segment (S6). 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 leafcutters of the subgenus Litomegachile include the following:  (1) the female Texas leafcutter has black bristles on the sides of the second through sixth segments of its abdomen (T1-T6); and  (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 here).

Distinctions between male Megachile mendica and M. texana are very subtle:  one difference is that white hairs rim T5 on the male M. texana but not on the male M. mendica.  Male M. texana also have conspicuous dark hairs intermixed with the light hairs on the thorax; and dark feet (tarsi).

Megachile texana

A Texas leafcutter bee (female)

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

Subgenus Eutricharaea
Subgenus Euticharaea

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 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.


These 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 its  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 and has a stout black body banded by  pale hairs; long white scopal hairs on the sternum (underside of the abdomen); a black head; greenish eyes; and white hairs lining the inner edges of the 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.  The striped pattern on the male alfalfa leafcutter's upper abdomen continues onto the underside (as shown in the photo strip here).  This is an identifying  trait of male leafcutters of the Eutricharaea subgenus.

Megachile rotundata

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

Alfalfa leafcutter bee

A female alfalfa leafcutter bee 

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

Subgenus Chelostomoides

Bellflower Resin Bee

Megachile campanulae

(Subgenus Chelostomoides)  

3/10 to 2/5"   (small to medium-sized)

Bellflower resin bees collect sticky plant and tree resins, which they use to seal the egg chambers of their nests. The bees construct nests in hollow plant stems or in tunnels left in wood by borer beetles.  The bees' eggs hatch in the fall, and the larvae then overwinter as pupae before emerging as adult bellflower resin bees in the spring.  These bees have been shown to engage in highly adaptive behavior when nest-building.  Studies conducted in 2003 revealed that bellflower resin bees have learned to collect resin from synthetic materials such as polyurethane-based caulk, in order to fortify the entrances to their nests.


Like leafcutter bees, bellflower resin bees are members of the genus Megachile and carry pollen on scopae located on their undersides, instead of transporting pollen on or under their legs like most bees. Bellflower resin bees, however, lack cutting blades on their jaws like those used by leafcutters.  This trait is common to the  subgenus Chelostomoides. 


Bellflower resin bees (Megachile capanulae) are native to America.  They were named in 1903 by the entomologist Charles Robertson, who noted their association with flowers of the genuscampanula known as bellflowers. Despite the name, these bees feed on a variety of flowers including milkweed, sunflowers, wild indigo, bee balm and members of the rose, pea and squash families.  The bellflower resin bees shown here were feeding on bellflowers, blue cornflowers and pea flowers in Stone Barns gardens, and on bird'sfoot trefoil and milkweed in the park.  Bellflower resin bees are important pollinators of both crops and native wildflowers.


Bellflower resin bees are preyed on by a species of cuckoo bee known as Stelis louisae, shown on the cuckoo bee page of this guide.  Stelis louisae  slip into bellflower resin bee nests, remove the resin seals from egg chambers, and destroy the resin bee eggs or larvae found within.  The cuckoo bees then lay their own eggs in the chambers and replace the resin seals over their openings.  When the cuckoo bee larvae hatch, they feast on provisions left by the bellflower resin bee for her own young.


Identification Information:  Bellflower resin bees are between 3/10 and 2/5"; females tend to be larger than males.  (The female shown here is  3/5" long and the male is 1/3" .)  Both males and females have long, parallel-sided black abdomens pitted with small indentations and banded by pale hairs. Females have white scopal hairs under their abdomens.  As shown in the photo strip here, female bellflower resin bees have four-toothed mandibles and distinctive, widely-spaced tubercules on the clypeus (the face part above the mandibles).


The male bee shown herein the photo strip has fairly exuberant pale hair on its face and shorter pale hairs on the top of its head and thorax.  The  white bands on the top of the male bee's abdomen continue onto its sternum (underside).  The last segments of the male bee's abdomen arch downward, curling under the bee so that they are not visible from above, a trait that helps distinguish males of the subgenus Chelostomoides from most North American leafcutter bee species.  Male bellflower resin bees have three-toothed mandibles.



Family:  Megachilidae

Tribe:  Megachilini

Genus:  Megachile

Subgenus:  Chelostomoides

Species:  Megachile campanulae

Megachile campanulae

A female bellflower resin bee 

Bellflower Resin Bee

A female bellflower resin bee on a pea flower.

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

Subgenus Callomegachile

Giant Resin Bee 
Megachile sculpturalis 

(Subgenus Callomegachile)  
1/2" - 1"  (large - medium-sized)

The giant resin bee is an invasive species from Japan and China that first entered the country in 1994. In Westchester, these bees have appeared in botanical gardens such as Lasdon Arboretum and John Jay Homestead's public herb & flower garden.  A single giant resin bee has been identified at Stone Barns Center for Food and Agriculture.


Giant resin bees belong to the subgenus Callomegachile -- and are the single representative of that subgenus in the United States. Like their native counterparts, female giant resin bees carry pollen on long hairs called scopae located on their undersides.


Giant resin bees have large mandibles, which they use for collecting resin and sap from conifers and maples trees.  The bees use these materials to construct sealed egg chambers in their nests. 


These non-native bees tend to occupy the abandoned nests of native eastern carpenter bees, located in dry rotted logs and wooden building structures such as decks, porches and eaves.  Giant resin bees do not bore holes in houses, however, because they lack cutting blades on their jaws.  


Although these bees have a scary appearance -- they look like evil Pokemon characters -- they are relatively harmless.  The males do not sting and the females are nonaggressive.  Giant resin bees are solitary and do not build communal or large nests.  Their general effect on native bee populations is not yet known, although they have been observed killing honey bees.

Identification Information:  Giant resin bees vary in size, from small males that are slightly larger than honey bees (about ½ inch") to females that are bigger than most bumble bees (nearly 1") . Giant resin bees have long, parallel-sided abdomens, sculpted black heads with large jaws, and mid-sections covered with brownish hairs.  The bees' heads are helmet-like and pitted with tiny indentations.  Their abdomens are also pitted and black.  Females' abdomens have pointed ends and males' abdomens blunt ends.  Giant resin bees hold their  wings  in a characteristic V position when resting on flowers.


Giant resin bees are pollinators of the pernicious invasive plant, kudzu.  They also pollinate some garden shrubs and trees, including catalpa, golden rain trees, bottlebrush buckeye, crepe myrtle and butterfly bush. 




Family:  Megachilidae

Tribe:  Megachilini

Genus:  Megachile

Subgenus:  Callomegachile

Species:  Megachile sculpturalis

Megachile sculpturalis

A female giant resin bee

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

This website's photos and text are protected by registered copyright. All photos are © 2014-2017 Paula Sharp & Ross Eatman, all rights reserved.  To inquire about possible use of photos, see Permissions. 


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

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