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Identification Guide to the Megachilidae Genera of Eastern North America

An identification guide to the genera of Megachilidae of North America. Includes illustrations, identification tips, distributional facts for separating out the genera

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Identification Guide to the Megachilidae Genera of Eastern North America

  1. 1. Chunky Bees that Carry Pollen Under their Abdomens: A Guide to their identification in Eastern North America
  2. 2. Acknowledgements <ul><li>This presentation has been put together by a consortium of North American bee biologists </li></ul><ul><li>This presentation has developed over many years and the original web picture acknowledgements were lost, if you see one of your pictures let us know and we will add your picture credit </li></ul><ul><li>Correspondence can be sent to Sam Droege at </li></ul>
  3. 3. Format <ul><li>Each Genus has an information page followed by a page of illustrations and a map of the distribution of Eastern North American species; western populations of Eastern species are shown, but the Western species are not mapped. </li></ul><ul><li>The number of Eastern species are listed at the top of the page </li></ul>
  4. 4. <ul><li>Anthidiellum – 2 species </li></ul><ul><li>Anthidium - 4 </li></ul><ul><li>Dianthidium - 3 </li></ul><ul><li>Paranthidium - 1 </li></ul><ul><li>Stelis - 12 </li></ul><ul><li>Trachusa - 5 </li></ul><ul><li>Hoplitis - 8 </li></ul><ul><li>Osmia - 28 </li></ul><ul><li>Ashmeadiella - 2 </li></ul><ul><li>Chelostoma - 3 </li></ul><ul><li>Heriades - 3 </li></ul><ul><li>Coelioxys - 24 </li></ul><ul><li>Lithurgus - 3 </li></ul><ul><li>Megachile - 40 </li></ul>
  5. 5. Anthidiellum <ul><li>Quite small, less than half the size of a honeybee </li></ul><ul><li>Fast flying, likes legumes, dry fields </li></ul><ul><li>Front of the mesepisternum (side facing the head) divided from the outward facing side by a sharp edge or carina </li></ul><ul><li>Unique in that the scutellum projects over the metanotum and propodeum as a THIN squared- off shelf, other species project a small amount but not as much and the edge is rounded over </li></ul><ul><li>Unique in that the sub-antennal sutures bend outwards </li></ul><ul><li>Similar Genera: Anthidium, Dianthidium, Paranthidium, Stelis, Trachusa </li></ul>
  6. 6. 2 Species, small, fast, likes legumes and dry sites
  7. 7. Anthidium <ul><li>2 common introduced species, 2 rare native species, most about the size of a honeybee or slightly smaller </li></ul><ul><li>Unique among genera listed below in that it has no pad or arolium between the tarsal claws at the ends of the legs </li></ul><ul><li>Female unique in that it has 5 or more teeth on the mandible </li></ul><ul><li>Similar Genera: Anthidiellum, Dianthidium, Stelis, Trachusa, Paranthidium </li></ul>
  8. 8. Some common introduced species 4 Species
  9. 9. Dianthidium <ul><li>A bit smaller than a honey bee, uncommon to rare </li></ul><ul><li>Has a small hollowed out area or fovea behind the spiracle on the rear face of the propodeum about the size of the spiracle </li></ul><ul><li>Front of the mesepisternum (side facing the head) divided from the outward facing side by a sharp edge or carina </li></ul><ul><li>Similar Genera: Anthidium, Paranthidium, Stelis, Anthidiellum, Trachusa </li></ul>
  10. 10. Uncommon to rare 3 Species
  11. 11. Paranthidium jugatorium <ul><li>Rare, but known to occur abundantly in at least one arboretum </li></ul><ul><li>Front of the mesepisternum (side facing the the head) NOT divided from the outer facing side by a sharp edge or carina </li></ul><ul><li>Front and middle tibia without a spine, the outer tip of tibia with a curved, transverse, projecting lamella, behind which the surface is shining and scoop-like </li></ul><ul><li>Margin of tip of mandible straight and at an oblique angle to outer margin, about half as long as mandible </li></ul><ul><li>Similar Genera: Anthidium, Anthidiellum, Dianthidium, Stelis, Trachusa </li></ul>
  12. 12. Uncommon, garden exception
  13. 13. Stelis <ul><li>Rare, one quarter to two-thirds the size of the honeybee </li></ul><ul><li>Nest parasites on Osmia, Megachile, Heriades, and Ashmeadiella and thus have no scopa on the underside of their abdomens like most other Megachilidae species </li></ul><ul><li>A variety of body types from very bright and colorful like Anthidium to dark and small like Heriades, some of these groups have been assigned Genus status in the past </li></ul><ul><li>Similar Genera: Trachusa, Anthidium, Anthidiellum, Dianthidium, Paranthidium, Heriades, Ashmeadiella, Chelostoma </li></ul>
  14. 14. Uncommon, parasites of Hoplitis, Osmia, Heriades, Ashmeadiella 12 Species
  15. 15. Trachusa <ul><li>Uncommon to rare, about the size of a honeybee </li></ul><ul><li>Front edge of scutum clearly raised above the pronotal collar </li></ul><ul><li>Similar Genera: Stelis, Anthidium, Anthidiellum, Paranthidium, Dianthidium </li></ul>
  16. 16. Uncommon, southern, 5 species
  17. 17. Hoplitis <ul><li>Relatively common dark brown, spring to early summer species </li></ul><ul><li>Parapsidial line on scutum long and similar to most other bee species </li></ul><ul><li>Males often have modified antennae with hooked ends or expanded segments </li></ul><ul><li>Similar Genera: Osmia, Heriades, Chelostoma, Ashmeadiella </li></ul>
  18. 18. Relatively common 8 species
  19. 19. Osmia <ul><li>Common spring to early summer species, ranging from one-third the size of a honeybee to slightly larger </li></ul><ul><li>The majority of species are dark blue (often appearing black in the field) with a few that are brown, black, and one rare bright green one </li></ul><ul><li>The parapsidial line of the scutum contracted to a line that is usually only 2-5 pit diameters long and is often difficult to find amidst the surface pitting </li></ul><ul><li>Differentiating males is particularly tricky as many of the best characters are on the underside of the abdomen and often hidden by retracted segments and curled abdomens </li></ul><ul><li>Similar Genera: Hoplitis, Ashmeadiella, Heriades, Chelostoma </li></ul>
  20. 20. Common, spring, hole-nester, 28 species
  21. 21. Ashmeadiella <ul><li>Rare, about one quarter the size of a honeybee </li></ul><ul><li>Front of the mesepisternum (side facing the head) divided from the outer facing side by a sharp edge or carina </li></ul><ul><li>Similar Genera: Heriades, Chelostoma, Stelis, Osmia, Hoplitis </li></ul>
  22. 22. Rare Small 2 species
  23. 23. Chelostoma <ul><li>Rare to Locally Common, Small, about one-quarter the size of a honeybee </li></ul><ul><li>Skinnier and more elongate than the other Megachilid genera </li></ul><ul><li>Head unusually long </li></ul><ul><li>2 introduced species now spreading slowly from New York and Ontario and pollen specialists on Campanula , 1 native species which is a specialist on Mock Orange ( Philadelphus ) </li></ul><ul><li>Similar Species: Heriades, Ashmeadiella, Osmia, Hoplitis, Stelis </li></ul>
  24. 24. Tiny, elongate, 3 species, 2 introduced
  25. 25. Heriades <ul><li>Uncommon, small, about one quarter the size of a honeybee </li></ul><ul><li>Has a very sculptured appearance with large diameter pits throughout </li></ul><ul><li>Upper surface of Propodeum is formed of a narrow row of open square cells defined by prominent raised lines </li></ul><ul><li>Unique within Megachilidae in that the portion of T1 that faces the thorax is hollowed out and surrounded by a raised line or carina </li></ul><ul><li>Similar Genera: Ashmeadiella, Chelostoma, Hoplitis, Osmia, Stelis </li></ul>
  26. 26. Tiny, uncommon to locally common, 3 species
  27. 27. Megachile <ul><li>Moderate to large, common particularly in the summer, from about half to 1.5 times the size of a honeybee </li></ul><ul><li>Most are black with thin white bands of hair on their abdomens </li></ul><ul><li>Males of some species have greatly expanded front tibia </li></ul><ul><li>Cutting edges of the mandibles often very useful in females but best seen by pulling open mandibles when specimens are fresh </li></ul><ul><li>Unlike genera listed below, has no arolium or pad between the tarsal claws of the legs </li></ul><ul><li>Similar Genera: Lithurgus, Coelioxys </li></ul>
  28. 28. Common in all open environments 40 species
  29. 29. Coelioxys <ul><li>Regular, but sparsely distributed, primarily out in the summer and early fall, most about the size of a honeybee </li></ul><ul><li>Nest parasites of Megachile and thus the females have no pollen carrying hairs under their abdomens </li></ul><ul><li>The axillae, which normally hug the edge of the scutellum, flare outwards and the shape of their tips are often diagnostic </li></ul><ul><li>Females have long, pointed abdomens, the shape of which is often unique </li></ul><ul><li>Males have an odd cluster of pointed or flattened projections and spines at the end of their abdomen, the pattern of which is also often unique </li></ul><ul><li>Similar Genera: Megachile, Lithurgus </li></ul>
  30. 30. Parasite of Megachile, pointed rear, arolia, no scopa 24 Species
  31. 31. Lithurgus <ul><li>Rare to locally common </li></ul><ul><li>2 native species are cactus ( Opuntia ) pollen specialists </li></ul><ul><li>The introduced species, L. chrysurus , is spreading slowly out of central New Jersey and eastern Pennsylvania and is a knapweed ( Centaurea ) pollen specialist and can be abundant when found </li></ul><ul><li>Often overlooked as Megachile (particularly males) but has an arolium or pad between its tarsal claws </li></ul><ul><li>Females all have a diagnostic and very prominent projecting flange between the clypeus and the antennal bases </li></ul><ul><li>Both males and females have a 3-lobed tip to the mandible </li></ul>
  32. 32. Rare, 2 cactus specialists, 1 introduced
  33. 33. Resources <ul><li>Species lists, Identification Guides, and Maps for genera and species are available at: </li></ul><ul><li> </li></ul><ul><li>A guide to the genera of the bees of Canada is available at: </li></ul><ul><li> </li></ul><ul><li>Mitchell’s 1960’s book on the bees of the Eastern United States is available as a series of pdf files at: </li></ul><ul><li> </li></ul><ul><li>A slightly out of date guide to the identification of the genera of ALL of North America is available at: </li></ul><ul><li> </li></ul>

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  • ketingler

    Nov. 17, 2009
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    Jun. 6, 2014
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    Dec. 12, 2014
  • BrianDykstra

    Jan. 13, 2017

An identification guide to the genera of Megachilidae of North America. Includes illustrations, identification tips, distributional facts for separating out the genera


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