Lyon County is experiencing our first large-scale fall invasion of the brown marmorated stinkbug.
They have been heavy in other counties of Kentucky for several years and have gained a foothold here. They join the ranks of the Asian ladybug in that they like to winter in our homes. Below is a primer on what’s happening and what you can do to try and curtail these stinky houseguests from Jonathan Larson, University of Kentucky Extension Entomologist.
Brown marmorated stink bugs (also known as BMSB) are an invasive species as well as “true bugs”-meaning they have needle-like mouthparts. Overall, these pests are shield-like in shape and a little over ½ inch in length. They get their name from their mottled brown and grey coloration. BMSB may damage garden plants, such as tomatoes and peppers, as well as tree fruits, such as apples and peaches, amongst others.
Insects don’t like the cold. Some insects are able to survive being frozen and others prevent being frozen by producing antifreeze compounds internally. Others try to escape the cold. In this group we have some species that migrate away from cold weather in order to survive. The most famous example of this is the monarch butterfly, which spends the winter in Mexico before they migrate north the following year. Then there are others that hide from the cold by finding somewhere that stays just warm enough to keep them safe. Usually this is done by hiding in leaf litter, getting under rocks, or burying into the soil. Other times, they might discover that humans have big, heated domiciles that they can easily sneak into!
BMSB falls into this last group. They overwinter as an adult and our homes mimic their natural hiding spaces with added amenities. Once they enter a home, they aren’t looking to feed or mate. They are simply waiting until spring. They usually enter a sort of arrested phase where they don’t move much. Occasionally though, on warm winter days, they will “wake up” and start crawling around the home.
Once winter is over, they leave their overwintering site in April and May to mate. The female lays eggs from May until August. After hatching, BMSB will develop through five nymphal stages before becoming an adult. Nymphs start out 1/8th inch and red and black; they become larger, darker, and browner as they develop. In September and October, adults begin searching for overwintering sites to start the cycle anew next year.
The best thing for homeowners to do is to start preparing in late summer.
• Inspect your home and check for cracks around windows, doors, pipes, and chimneys and seal openings with silicone or silicone-latex caulk.
• Turning off exterior lights or switching to non-insect attracting bulbs will reduce stink bug interest in your structure.
• If stink bugs are found inside, simply vacuum up living specimens and dispose of them outside.
• Using bug bombs or other insecticides in the home will not help to deal with stink bugs and will only serve to expose the people inside to residues.
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