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Giant Resin Bee - Megachile sculpturalis - (c) Copyright 2015 Sharp-Eatman Photo


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 and belong to a different 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 genera campanula 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 are 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 considered 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 bees 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 at right, female bellflower resin bees have four-toothed jaws without cutting edges and distinctive, widely-spaced tubercules on the clypeus above their jaws.


The male bee shown here (in the phtostrip at right) 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 male bellflower resin bees from many leafcutter bee species.  Male bellflower resin bees have three-toothed jaws.



Family:  Megachilidae

Tribe:  Megachilini

Genus:  Megachile

Subgenus:  Chelostomoides

Species:  Megachile campanulae

Bellflower Resin Bee

Megachile campanulae  

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

Giant Resin Bee 
Megachile sculpturalis 
1/2" - 1"  (large - medium-sized)

Bellflower Resin Bee - Megachile campanulae - (c) 2015 Sharp-Eatman Photo
Giant Resin Bee - Megachile sculpturalis - (c) 2015 Sharp-Eatman Photo

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.


Like the two native resin bees shown below, giant resin bees are members of the genus Megachile. Within that genus, giant resin bees belong to a different 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

A female bellflower resin bee on a pea flower.

A female giant resin bee

Bellflower Resin Bee - Megachile campanulae - (c) 2015 Sharp-Eatman Photo

A female bellflower resin bee with white scopal hairs under her abdomen

Heriades are native resin bees equiipped with mandibles designed to scrape resin from plants.   Like the bellflower resin bees shown above, Heriades bees use resin to plug their egg-chamber tunnels.  Heriades bees nest in pre-existing holes they find in wood and hollow stems. 


Although similar in appearance to the bellflower resin bee, Heriades bees are significantly smaller. The bees shown here are between 1/5" andis just under 1/4" in length.  Heriades resin bees are black with conspicuous indentations pitting their heads, thoraxes and abdomens. Females carry pollen on the undersides of their abdomens like the other resin bees shown on this page.  Male Heriades bees' abdomens have a distinctive downward curve.  Both males and females's dark abdomens are striped with pale hair bands.

Heriades resin bees have been documented gathering pollen from a variety of plants, including, among others, agastache, allium, butterfly weed, coreopsis, fleabane, goldenrod, marjoram, mountain mint, sumac, swamp milkweed, spreading dogbane, wild bergamot and members of the squash family.


There are at most three or four species of Heriades resin bees in the New York area.  The female bee at top right has been identified as belonging to one of two very similar resin bee species -- Heriades leavitti or Heriades variolosa. This resin bee was found foraging on orange butterfly weed (Asclepias tuberosa) in the VIsitor Center garden of Rockefeller Stte Park Preserve in early July, 2017.  


The second bee at right is a Heriades carinata.   This bee  has a keel-like structure, called a carina, on its mandibles.  This trait is diagnostic of the species.


Heriades carinata resin bees reportedly do not emerge until the weather grows hot. These bees appear in the vegetable and cut-flower fields of Stone Barns Center for Food and Agriculture in August.


Heriades carinata bees are reported to be energetic pollinators of onions and  leeks.The Heriades carinata bee shown here was found feeding on fringed quickweed, a plant of Mexican origin now naturalized in the United States and belonging to the aster family.  This naturalized weed self-seeds in Stone Barns' dahlia and strawflower beds. 




Family:  Megachilidae

Tribe:  Osmiini

Genus:  Heriades

Subgenus:  Neotrypetes
Species:  Heriades carinata


A Note on the Taxonomy of Resin Bees.   Resin bees share the defining trait of using their mandibles to scrape resin and sap from plants, which the bees mold to form plugs for their nest openings.  The name "resin bee" can be confusing, however,  because there are different kinds of resin bees belonging to different bee tribes and genera (genuses). 


Resin bees, along with leafcutter bees, mason bees and carder bees, belong to the scientific family Megachilidae and to the subfamily Megachilinae.  All of these bees share the habit  of transporting pollen on scopae (sticky hairs) on the undersides of their abdomens. 


The subfamily Megachildae is further divided into tribes.  These include:  

(1) The tribe Megachilini :  This contains the genus Megachile, which includes leafcutter bees and two of the resin bees shown on this page - -- the bellflower and giant resin bee. 

(2) The tribe Anthidini:   This includes wool carder bees and the cuckoo bee Stelis louisae, which preys on bellflower resin bees. 

(3) The tribe Osmini:   This contains mason bees in the genera (genuses) Osmia, Hoplitis and Chelostoma -- and it also includes resin bees belonging to the genus Heriades -- like the Heriades carinata bee shown here.

Heriades carinata Resin Bee

Heriades carinata

1/6" to 1/4"   (small)

Heriades variolosa /  leavitti Resin Bee

Heriades variloosa / leavitti

1/5"   (small)

Heriades carinata Resin Bee - (c) 2015 Sharp-Eatman Photo

A female Heriades carinata resin bee

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

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

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

Heriades leavitti / variolosa Resin Bee - (c) 2017 Sharp-Eatman Photo

A female Heriades leavitti / variolosa resin bee

PHOTO CREDITS:  All photos and text © Copyright 2014-2017 Paula Sharp and Ross Eatman, unless otherwise noted.  All rights reserved. If you wish to use any of the photographs here for educational or other purposes, please read permissions page.


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

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