Wasp Watcher
Cerceris fumipennis
How to find the wasp that hunts emerald ash borer
This native wasp is not known to sting humans, even when handled.
Female Cerceris with Emerald Ash Borer
Cerceris fumipennis is a solitary ground-nesting wasp. The female stocks her nest with buprestid beetles, including emerald ash borer (EAB) when present.
Biosurveillance (observing colonies of these native wasps and collecting some of the prey they bring back) is currently the most promising way to monitor for EAB. The Maine Forest Service is looking for colonies of these wasps throughout the state, and would like your help.
Identifying Markings
- ½ - ¾ inch long
- dark smoky brown wings
- one cream/yellow band on second segment of abdomen (near “waist”)
- three large cream’/yellow spots on face
Markings of Female Cerceris fumipennis
(photos by P. Careless)
In New England Cerceris can be found only in July and August
(Cerceris is pronounced: 'ser-ser-iss)
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What are Promising Nest Sites?
- hard packed sandy soil
- areas of human disturbance where the disturbance has been present for more than three years.
(school playing fields, baseball diamonds, trail and road edges, informal parking lots, fire-pits, camp-sites, etc.)
- full sunshine
- sparse vegetation (about 50% hard-packed soil and 50% short vegetation)
- near a wooded area (about 200 yards or less)
Typical Cerceris Colony Sites
(photos by P. Careless)
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How to Identify Nests
- round holes the diameter of a pencil
- holes go straight down (not angled into the ground)
- surrounded by a circle of excavated soil (not all to one side like a dog would dig)
- often tucked beside or under a clump of grass
- from 3-300 nests in a colony
Tip: Until you become familiar with Cerceris nests, carry a small piece of plastic or cardboard with a standard "hole punch" hole in it. This is about the size of a nest opening.
Cerceris Nests
(photos by P. Careless)
(Remember, if you want to monitor these colonies for EAB, they should be within 400 yards of ash trees.)
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Biosurveillance
- Carry out biosurveillance at your site 3-4 warm sunny afternoons during July.
- Choose 30-100 nests in one area (as many as you can keep an eye on).
- At each nest, pin the ‘collar’ to the ground with golf tee, placing the second hole over the nest entrance.
- Wasps without prey can come and go easily through the hole (A). A wasp carrying prey will not fit through the hole (B).
- For 1-3 hours, watch as wasps return to nests. Wasps with prey can be netted in flight or caught as they try to pass through the collar. Take prey and release wasp.
- Collect a total of 50 beetles over 3-4 visits. Place beetles from each day in a baggie labeled with place and date. Place in freezer and mail to us at end of summer.
A - Wasp Entering Nest Through Collar
B - Wasp Unable to Enter With Prey
(photos by P. Careless & M. Bohne
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What is Emerald Ash Borer?
- Small metallic green beetle (1/2” long, 1/8” wide)
- An exotic beetle from Asia
- Larva tunnels under the bark
- Attacks and kills all species of ash
- First found in Michigan in 2002
- Spreading VERY rapidly across the USA and Canada (primarily in firewood)
- Early detection is difficult. This wasp and WaspWatchers can help.
Emerald Ash Borer
If you think you have found a Cerceris colony or would like more information, please contact:
Colleen Teerling: colleen.teerling@maine.gov
phone: (207) 287-3096
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