'Tis the season for home invasion from two tiny pests.
When soybean fields are harvested, rural community residents are used to an influx of Asian lady beetles, which originally were introduced to the United States to help farmers control the pecan aphid. This year, Kelly Allsup is warning of a second unwelcome visitor.
"Another new potential home invader may be looking for a spot to overwinter in Illinois homes this year, and that is the brown marmorated stink bug," said Allsup, a University of Illinois Extension horticulture educator, in a news release. "We have heard about invasions of homes in the Mid-Atlantic states in the past. They are a nuisance because they do what stink bugs do best — stink, but only when threatened."
Inside the house, stink bugs pose little threat aside from unleashing unpleasant odor. Outside, however, they can be destructive.
"(Stink bugs) are capable of causing economic losses to soybean and corn producers," said Mike Gray, a University of Illinois Extension entomologist, in a news release.
The invasive insect first was identified in 1998 in Pennsylvania and is considered a stowaway from Asia. Brown marmorated stink bugs feed on the landscape, native and agriculturally important produce.
According to a new study by a University of Maryland entomologist, adult stink bugs have a strong preference for ripe fruit, leaving the nymphs to eat other plant material. This has caused many growers on the East Coast, where the insect population has skyrocketed, to forfeit efforts to be organic and start using chemicals. Traps also have been developed using an aggregation pheromone.
The stink bug has piercing mouthparts and is capable of damaging a multitude of crops from apples to pears to soybeans and ornamental landscape plants.
Damage to Illinois crops has been kept minimal.
"The combination of lower populations of (brown marmorated stink bugs) and highly managed crop systems in Illinois have kept detection and economic injury levels low," said Kelly Estes, state survey coordinator at the Illinois Cooperative Agriculture Pest Survey Program, in a news release.
Estes said reports of stink bug sightings typically come from urban areas in the early spring and fall when homeowners detect the insects entering their homes to escape the cold.
Stink bugs are expanding their territory, according to the Extension, with almost half of Illinois counties having positive identification of the species. Seven new counties have confirmed the insect's presence this year. However, the USDA currently classifies Illinois as being at low risk for the pest, as large numbers have not been recorded.
Allsup encourages homeowners and gardeners to be on the lookout for this invasive pest as in the past few weeks she has found five brown marmorated stink bugs on the screens of her windows at her Bloomington home.
To identify a brown marmorated stink bug, look for these characteristics: the body has the shield-shape characteristic to stink bugs and it is as wide as it is long; the three most identifying characteristics are its black and white banding on the antennae and the alternating dark/light banding on the edge of the wings and the smooth shoulders.
After overwintering in April, the adult stink bug can lay 20 to 30 eggs, with nymphs emerging shortly after. There can be multiple generations per year depending on seasonal temperatures.
Like stink bugs, Asian lady beetles like to overwinter in homes. If there is a crack or crevice opening into a house, it may be vulnerable to the beetles and stink bugs.
The Asian lady beetle can be identified from the native ladybug by the black M shape just behind its head. Although Asian lady beetles do not reproduce indoors or harm interiors, they emit a foul odor, stain surfaces and occasionally bite.
Battling a bug home invasion
To eliminate Asian lady beetles and brown marmorated stink bugs in the home, follow these tips:
- Use a vacuum to suck up adults or drop them in soapy water.
- Take steps in early fall to caulk cracks and crevices around 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.