Elm Seed Bug (Arocatus melanocephalus)
Detailing the identifying qualities of the Elm Seed Bug, including physical features and territorial reach.
Updated: 1/25/2017; Authored By Staff Writer; Content ©www.InsectIdentification.org
The name and large swarming tendencies of Elm Seed Bugs suggest it is dangerous, but the harmless insect is really just a seasonal nuisance.
First sighted in 2009 in counties in Idaho, the Elm Seed Bug is native to Europe and how it came to North America is unknown. It is a relative of Boxelder Bugs and Stink Bugs, and like them, produces an odor when crushed or smashed. What makes them so troublesome is their swarming nature. Hundreds of them congregate and have a tendency to find their way indoors. They do not harm people, or even the tree they are named after, but the infestation inside a home is naturally disturbing. Because adults do not die in winter, they tend to look for warmer places to ride out the cold weather. They also tend to look for cooler environments in the hot summer, so ridding a house or building of them may be a biannual chore.
Government agencies in Idaho and Utah suggest vacuuming (using a Shop-vac or other brand of workshop vacuum) any swarms that get inside, and establishing routine insecticide treatments around the perimeter of the house or building as well as window wells, and door frames. Prevention of invasion is easier than removal, so raking up and destroying fallen elm seeds, and inspecting firewood before bringing it indoors are recommended.
Larval Elm Seed Bugs feed on the seeds of elm trees during the spring and early summer. They are therefore likely to be found in neighborhoods or regions where elms are present.
Our thanks to Fred and Jan T. in Idaho for their assistance in identifying this insect.