State agriculture officials announced Wednesday that they’ve confirmed two new invasive insects in Minnesota.
The elm seed bug and the Asiatic garden beetle were discovered in August by homeowners in the Twin Cities who reported them to the Minnesota Department of Agriculture’s Report a Pest program.
State officials described the elm seed bug as mostly a “nuisance pest” like box elder bugs. Meanwhile, they said Asiatic garden beetles can feed on and defoliate more than 100 kinds of plants.
The Department of Agriculture is asking people to report suspected sightings of the two insects, so officials can gain a better understanding of where they may be in the state.
Grow the Future of Public Media
MPR News is supported by Members. Gifts from individuals power everything you find here. Make a gift of any amount today to become a Member!
Elm seed bug
This invasive insect — native to Europe and first confirmed in the U.S. in 2012 — has “piercing sucking mouth parts and primarily feeds on elm seeds but can also feed on linden and oak,” the Department of Agriculture reported.
The bugs can enter homes in large numbers like box elder bugs — but while box elder bugs are active in late summer and fall, elm seed bugs tend to be active in mid-June. The first confirmed sighting in Minnesota was in Minneapolis.
The Department of Agriculture described them as one-third of an inch long. They’re “a dark rusty-red and black color. The underside of the insect is red. On the back behind the head, there is an upside-down black triangle set inside two rusty-red triangles. Next to the edges of the wings where the abdomen is exposed are alternating white and rusty red-black patches.”
The best management approach, officials said, is to seal cracks and gaps on the exterior of buildings so the insects can’t get inside.
Asiatic garden beetle
Asiatic garden beetles feed “on over 100 hosts, including fruit, vegetables, perennials, and annuals,” the Department of Agriculture reported. “Grubs prefer roots of ornamentals and garden plants. Preferred hosts include butterfly bush, rose, dahlia, aster, and chrysanthemum.”
Adult beetles feed on leaves and flowers, and “heavy infestations can lead to complete defoliation except for the leaf midribs.”
The insects are native to Japan and China, and have been found in the U.S. for more than a century; the first report was from New Jersey in 1922. There’s an established population in New England, and it’s also been found in Illinois and Indiana. The first confirmed sighting in Minnesota was in St. Paul.
The Department of Agriculture described them as about three-eighths of an inch long. They are “chestnut brown, and may have a slight iridescent sheen. The abdomen protrudes slightly from the wing covers. Adults emerge at night and fly actively when temperatures are above 70 degrees Fahrenheit. They are related to Japanese beetles but differ in that Japanese beetles fly and feed during the day and Asiatic garden beetles feed at night.”
Anyone in Minnesota who suspects they’ve seen elm seed bugs or Asiatic garden beetles is asked to report those sightings to the Minnesota Department of Agriculture’s Report a Pest program online, or call 888-545-6684.