Dealing with Household Overwintering Insects: Stink bugs and flies, oh my!

Posted by

Insects are fantastic creatures. We marvel at their various shapes, sizes, colors, and behaviors. Well, maybe not everyone. While it is my hope we all have that inner entomologist, it is more likely many of us harbor an inner exterminator.

One reason winters can be quite enjoyable is that we get a reprieve from many of the nuisance insects. When going to the playground, instead of covering ourselves with insect repellent, we just layer on the winter clothes. When going for a jog, we aren't accidentally swallowing buffalo gnats or swatting at mosquitoes while working in the garden.

However, some insects find our warm homes enticing in the winter. Perhaps you have had to deal with lady beetles, box elder bugs, or even the rogue wasp. This winter our Extension office has received several calls regarding three particular unwanted houseguests: brown marmorated stink bug, cluster flies, and black blow flies.

Brown marmorated stink bug (BMSB) hails from Asia and has few natural predators in North America, allowing it to spread quickly in the United States. Grapes, orchard crops, many landscape ornamentals, small fruit, vegetables, and field crops are all on BMSB's menu, making it a serious pest. After BMSB is finished feeding on our plants in the summer, this outdoor pest can easily move indoors, becoming a household nuisance.

As the name implies, BMSB emits a foul odor when crushed, so a rolled newspaper won't work in this situation. Sweeping with a broom or designating a shop-vac to rid your home of BMSB is your best option. Don't use your regular vacuum as the stench left behind in your filters and canister will forever potpourri your house with Eau de Stink bug.

Cluster flies appear similar to the common house fly at about one-quarter inch long. Cluster flies are not considered filth flies. Instead of feeding on rotting materials or manures, cluster fly larva parasitizes earthworms in the soil. Cluster flies spend most of the summer outdoors and then will often overwinter in large aggregates (clusters) behind siding, attics, or wall voids.

Black blow flies also overwinter in homes. The black blow fly can be considerably larger than the common house fly at one-half inch long. Blow flies feed on dead animal carcasses such as a mouse in a wall void. A single mouse cadaver will produce about 120 blow flies.

According to Extension entomologist, Phil Nixon, sunny days and longer daylight may draw cluster flies and blow flies out in the open. This weather change often corresponds to the Groundhog Day tradition. When the flies emerge in mid-winter, they will use up their stores of energy and die. One can hurry that along with a flyswatter. If found inside, these flies can be vacuumed up or swept into a dustpan and discarded.

For both BMSB and overwintering flies, the best control is prevention. Closing entrance points to the home will keep these nuisance insects out of the home. Fill in cracks around windows, doors, utility access points, air-conditioners, air vents, chimneys, soffits, gaps in siding, and holes with caulking compounds. Household overwintering insects tend to be attracted to the warmer temperatures on the sunny side of structures. Repair screening and keep outdoor lighting to a minimum or use non-attractive insect lights.

Pesticides are not recommended for indoor control of BMSB or cluster flies. These creatures overwinter in large groups and killing them with foggers or sprays will leave behind a considerable amount of dead insects. Secondary infestations may then occur with rodents, cockroaches, or carpet beetles that find a dead bug buffet awaiting in your walls and attics.

Do you have insects invading your home? Snap a picture to email or bring the specimen to your local Extension office for identification and control recommendations.