Forestry & Wildlife

Alabama Invader: Sculptured Resin Bee

4 min read
Sculptured resin bee

Some invasive species are obvious. Damage to fields from feral hogs is easily visible, whole buildings and forests can be covered by kudzu, and pastures dominated by cogongrass stand out readily. Other invasive species are more subtle, especially when they resemble more familiar natives. The sculptured resin bee (Megachile sculpturalis) is one such species. Most people in Alabama are likely to recognize a carpenter bee, the familiar and troublesome insect that damages all manner of wooden structures as it excavates its nests. However, what may at first glance look like a carpenter bee may not be what it seems. Instead, it may be a sculptured resin bee, which closely resembles the native look-alike. Introduced from east Asia, this bee now persists across much of the eastern United States. The effects of this exotic insect on native species and on the ecology of the region is still poorly understood but worthy of more attention.

Causing Problems

Side view of a sculptured resin bee.

Side view of a sculptured resin bee. (Photo credit: © Jesseholifield, iNaturalist.org (CC BY-NC) some rights reserved)

The sculptured resin bee is a commonly observed species in many parts of Alabama, having been present in the state since approximately 1999. It has been found to readily, even preferentially, pollinate exotic plant species over native ones The high occurrence of Asiatic plants—such as Chinese privet and kudzu—may be aiding in the spread of the sculptured resin bee. Also, the presence of a natural pollinator of these plants may, in turn, further the spread of these and other invasive plants.

Outside of its relationship with invasive plant species, the sculptured resin bee does compete directly with Alabama’s native pollinators. It is a solitary bee, with females making tunnel nests to store the food that their larva need to grow. It will nest in any appropriately sized and placed cavity, whether naturally occurring hollow stems, the burrows of wood boring beetles, or the cavities excavated by similar-sized bees. It is actively antagonistic with carpenter bees (Xylocopa spp.) and will attempt to evict them from burrows or even kill them. It may also compete with other native bees, such as mason bees (Osmia spp.), for cavities as well.

Identification

The sculptured resin bee is one of the largest bees occurring in the United States. It ranges from ¾ of an inch to 1 inch in length. It is a large-headed bee, with females in particular having prominent jaws. Males have a hairy patch on the front of the head but females do not. The thorax and parts of the abdomen have a covering of brownish-yellow hairs, with the abdomen being proportionally long and cylindrical. Compared to its native doppelgänger, the abdomen of a sculptured resin bee is rougher and more matte in appearance. The wings are brownish in color.

The native carpenter bee (Xylocopa spp.) is proportionally shorter bodied than the resin bee is. Its abdomen is wider, rounder, and shinier. The head of the carpenter bee is proportionally smaller and lacks the heavy jaws of the resin bee. The hair on the thorax is thicker and more vibrant yellow in color, and the wings are less dark and more yellow in tone as well.

The side profile, dorsal top, front, and bottom of a male eastern carpenter bee (Xylocopa virginica)

The side profile, dorsal top, front, and bottom views of a male eastern carpenter bee (Xylocopa virginica)

The carpenter-mimic leafcutter bee (Megachile xylocopoides) is significantly smaller and darker than the resin bee is. While it has a comparably large head and jaws, its body is much glossier, with only a small amount of black hair. Its abdomen is flatter and more pointed, with longer hair on the underside. Its overall coloration is darker and bluer in tone, with dark wings. The carpenter-mimic leafcutter bee also lacks the brown or yellow colors of the resin bee.

The carpenter mimic leafcutter bee (Megachile xylocopoides is named for its superficial similarity to the carpenter bee genus Xylocopa.

The carpenter-mimic leafcutter bee (Megachile xylocopoides) is named for its superficial similarity to the carpenter bee genus, Xylocopa.

Action Steps

Unfortunately, this species is one of the more commonly observed bee species in parts of Alabama. Preventing further spread within the state is no longer especially viable. However, it is still possible to gain a greater understanding of the effects it has on native ecologies and to limit its presence through several potential steps.

  • As with any invasive species, it is recommended to report suspected sightings of this species to EDDmapS, iNaturalist, or the Alabama Cooperative Extension System. This provides a better understanding of distribution and population density and allows for more targeted management.
  • Avoid planting exotic plants that this species may prefer as a food source.
  • Do not transport firewood or other potentially infested lumber between counties.
  • If this species is found to be utilizing bee hotels meant for native bees, remove the parts of the structure being utilized and dispose of them.
  • As the sculptured resin bee readily utilizes the burrows of carpenter bees, it is possible that traps meant for carpenter bees will also be effective at trapping this species as well.

References

 

Featured photo credit: © Jesseholifield, iNaturalist.org (CC BY-NC) some rights reserved