Asian lady beetle ‘invasion’ is both beneficial and annoying

They’re everywhere. Ladybugs cling to students’ clothes, attach to campus connectors and swarm inside houses. These multicolored Asian lady beetles are raiding campus.

“I remember waking up in the middle of the night, and there was one crawling up my pant leg,” senior Angela Lane said.

Asian lady beetles appear in late fall in search of places to hibernate.

“There are no mountains or cliffs (to hibernate in), so the next best thing is a house,” said Bob Koch, a graduate student and research assistant in the University’s entomology department.

The first Asian lady beetles were imported as early as 1916 to combat aphids and other agricultural pests in the southeast United States. But the beetles weren’t prevalent until the 1980s, Koch said.

The beetle was first discovered in Minnesota in 1994, clinging to Hodson Hall on the University’s St. Paul campus.

Asian lady beetles continue to serve their pest-control purpose. They eat many crop-killing insects and allow farmers to use fewer insecticides, benefiting both the environment and farmers’ pocket books.

Those annoyed by the bugs should not resort to violence – harming these beetles elicits more problems.

When the lady beetles are threatened or killed, they ooze blood from their leg joints, a process called “reflex bleeding,” Koch said. This orange-colored, bitter, and foul-smelling secretion acts as a defense mechanism against potential predators.

The blood is not poisonous, but it can stain carpet, clothes or other light-colored objects.

To keep the beetles from entering your house, seal holes in screens and caulk holes in the exterior of houses. If they’ve already gotten in, vacuum them up then release them outside.

However, the beetles are becoming more than an annoyance to some. They’re affecting business.

Much of the Minnesota wine industry is affected by the beetles.

“These nasty pests have been a serious pest problem for vineyards,” said Paul Quast, a University alumnus and winemaker at Saint Croix Vineyards.

Asian lady beetles converge on damaged grape clusters as a source of food. When the grapes are processed, many beetles are crushed, contaminating the grape juice and wasting the wine.

The lady beetle population will fluctuate, Koch said. For now, Minnesota will have to coexist with these invaders.