I was transplanting a few Blue Mistflower (Conoclinium coelestinum) plants into my drainage swale pollinator garden last weekend when I noticed this new insect visitor to my blooming Rattlesnake Masters (Eringium yuccifolium; below). 

This gentle beauty has a name that could have been penned by a cowboy poet – Smoky-winged Beetle Bandit Wasp (Cerceris fumipennis; Family Crabronidae) – and it plays an important ecological role. It parasitizes adult metallic wood-boring beetles of the family Buprestidae, including oak-boring beetles and the Emerald Ash Borer (Agrilus planipennis), an invasive beetle that is devastating North American ash trees, especially Green and White Ashes (Fraxinus pennsylvanica and americana). 

The Smoky-winged Beetle Bandit Wasp is native to Eastern North America and is the only North American wasp known to parasitize adults of Buprestid wood-boring tree pests, using the beetle bodies as hosts for their eggs and larvae. Scientists have even used this species for biosurveillance to monitor range expansion of the Emerald Ash Borer.

A combination of traits can help identify this native parasitoid wasp. Look for its black head, thorax, and abdomen and smoky-brown wings. Females may have a blue reflection to their wings. A distinctive cream or white apical band on the second abdominal segment is another key characteristic. Females have three cream-colored spots on the face, while males have two yellow triangles between their eyes. 

Smoky-winged Beetle Bandit Wasp adults are active mid-June into September in the northern part of their range. They are solitary ground-nesters that generally produce two generations annually. According to Heather Holm (2021), they usually burrow into compacted sandy or gravelly soil along rivers, in paths, gravel parking lots, or even baseball diamonds, frequently near forests where they can hunt for their beetle victims in the tree canopy, then bring them back to the nest. A female captures and injects a beetle with venom, then carries it in her mandibles to stash with several other paralyzed beetles in an underground nest chamber. 

She’ll lay one egg on the top beetle that hatches after several days. She provides a larger supply of beetles for her female offspring than for the males. After hatching, her larvae will remain in their underground chambers over winter, feasting on beetles from their own personal stockpiles, before emerging as adults the following summer.

Biologists can observe the beetles that female wasps bring back to their ground burrows to document the presence of these tree pests.

These beneficial wasps are also “accidental” pollinators that pick up pollen on their bodies and transport it to other flowers while nectaring. They are harmless to humans and defenders of our forests, so two things we can do for them in return are protecting their nest burrows when we find them and providing some of their preferred nectar plants in a sunny spot near the forest, like rattlesnake master, swamp or butterfly milkweed (Asclepias incarnata or tuberosa), Virginia mountain mint (Pycanthemum viginianum), daisy fleabane (Erigeron strigosus) and Canada goldenrod (Solidago canadensis). These are relatively simple pest management practices for forest conservation that will also benefit many other pollinators.

While one species of wasp alone may not entirely solve the widespread dilemma of invasive wood-boring tree pests, there are other introduced and native parasitoid wasp species and woodpeckers that target earlier stages of the Emerald Ash Borer life cycle (egg and larval) (Shrewsbury 2026). Therefore, working in combination with other species, they could make a real difference for the next forest generation and therefore deserve our conservation attention.

By Stacy Small-Lorenz, UME Residential Landscape Ecology Specialist

This article was originally published in the UME IPM Weekly Report on August 7, 2026

References: 

Holm, H. 2021. Wasps: Their Biology, Diversity, and Role as Beneficial Insects and Pollinators of Native Plants. Pollination Press LLC. Minnesota, USA. 420 pp.

Shrewsbury, P. 2026. The Exciting Life of Parasitoids and Their Role as Biological Control Agents. Presented at the Stanton A. Gill Symposium: A Focus on Biological Control. August 5, 2026. University of Maryland Extension, Clarksville, MD.