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Typically, Asian lady beetles are on the top of our home invader list in Illinois. They were released to help farmers with pecan aphids, but they like to invade our homes instead of overwintering in the cliffs of their native land.

If there is a crack or crevice leading to the inside of your home, you may be vulnerable to this and other unwanted inhabitants.

They usually congregate on an outside wall after a warm period following a freeze, attracted to the sunlight emitting off a south or southwest wall. They can be identified from the native ladybug by the black M shape just behind their head. Although they do not reproduce indoors or harm anything inside, they emit a foul odor and occasionally bite.

A new invader looking for a spot to overwinter in Illinois homes is the brown marmorated stink bug. They do what stink bugs do best – stink — but only when threatened.

This invasive insect was first identified in Pennsylvania in 2001 and was a stowaway from Asia. Brown marmorated stink bugs have piercing mouth parts and can damage a multitude of crops, from apples to pears to soybeans to landscape ornamentals.

A University of Maryland entomologist says adults have a strong preference for ripe fruit, leaving the nymphs to eat the plant material. This has caused growers on the East Coast, where the population has skyrocketed, to forfeit all efforts to be organic and instead pull out their arsenal of chemicals.

Kelly Estes, state survey coordinator at the Illinois Cooperative Agriculture pest survey program, previously has written that "the combination of lower populations of BMSB (stink bugs) and highly managed crop systems in Illinois have kept detection and economic injury levels low."

But, Estes added, "Most reports of this insect have come from urban areas in early spring and fall, generally from homeowners and Master Gardeners."

The bugs are expanding their territory, with almost half the counties in Illinois with positive identifications and seven new counties this year with positive confirmations, including Woodford. McLean found its first brown marmorated stink bug in 2011. I have found them in my home and office.

The bug as the shield-shape characteristic to stink bugs and it is as wide as it is long. The three most identifying characteristics are black and white banding on the antennae, alternating dark/light banding on the edge of the wings, and smooth shoulders. 

To control Asian Lady beetles or black marmorated stink bugs in the home:

  • Use a vacuum to suck up adults or drop them in soapy water
  • Take steps in early winter to caulk the house
  • Prevent movement in from the outside by repairing windows and putting on door sweeps
  • It is not recommended to use sprays in the home because insecticide residues are relatively ineffective in providing control.

Kelly Allsup is the University of Illinois Extension horticulture educator in Livingston, McLean and Woodford counties.


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