Overwintering Pests:   What Are They And What Can You Do About Them?

Overwintering Pests: What Are They And What Can You Do About Them?

Captain Stan The ‘Fall Invaders’ Man VP, Technical Products and Services, AP&G (Catchmaster) Captain (Retired), United States Navy November 2022 Note: With mosquito season winding down in most of the country, CAPT Stan branches out to take a look at a group of insects that can be troublesome this time of year. A group of various insects are collectively referred to as ‘Fall Invaders’ or ‘Overwintering Pests.’ They survive cold weather by hibernating in the void spaces of structures, including customers’ homes, factories, distribution centers, etc. They are attracted to these structures in search of an ideal warm resting site to pass the winter. You will usually see them on the west and south walls of the buildings, which are heated by the sun. This annoying migration is triggered primarily by shortening daylight hours and cooler temperatures. Normally, it is only the adult stage that is found indoors. Once inside, they slow down their metabolism, minimize other bodily functions, and hunker down to wait for the arrival of spring and warmer days. A few fall invaders may constitute just a nuisance but in larger numbers, they can exceed nuisance status, especially in sensitive accounts ( e.g. food production facilities, health care facilities, day care centers). Some can stain surfaces and create odors in addition to being a contamination threat. It may help with any customer ‘angst’ to stress that once inside the structure, fall invaders:
  • Do not breed,
  • Do not feed,
  • Do not develop further.
Four of the most common fall invaders are:
  • Box Elder Bug – likely the most common of fall invading insects, adults are about ½ inch long, mostly black in color, with red lines marking the wings and thorax (area behind the head).
  • Brown Marmorated Stink Bug (BMSB) – the BMSB is one of our newer invasive pests, which has moved from its introduction point in eastern Pennsylvania to the west. It is both an agricultural and structural pest. BMSBs have a mottled brown color and are shield-like in shape. They measure about 5/8 of an inch and have lighter bands or stripes on the antennae.
  • Multi-colored Asian Lady Beetle – they get their name because they come in a variety of colors and markings. Wings can be tan to reddish orange with a varied number of black spots. This invader is especially noticeable around and just after Halloween.
  • Cluster Fly – as the name implies, these often appear in structures in clusters. The adult cluster fly is slightly larger than the house fly. Wings are held overlapping each other over the abdomen. Interestingly, the immature stages are parasitic on earthworms and cause no structural damage.
How Do We Control Fall Invaders? The first line of defense against fall invaders is exclusion, which is obviously best done BEFORE they enter a structure, such as in the summertime. The primary tools are sealants, door sweeps, and screens, making sure that the latter two are in good repair. These invaders don’t require a gaping opening to enter; the multicolored Asian lady beetle can fit through a hole 1/8 inch! Special attention should be given to the south and west exposures of structures, as these are the sunnier sides where fall invaders tend to congregate and attempt to enter. Perimeter applications of insecticides can be used to supplement exclusion. Focus on the areas where pests could enter the structure and be sure to read the label prior to any treatment. There may be some restrictions. Treatments done after pests have entered the structure are of minimal value. Once insects make their way in, insect light traps can be used in open or occupied spaces of the structure/home. Insects may be fooled into emerging from voids or other protected places if outdoor temperatures warm. Many times, it is easiest and most effective to simply vacuum the pests but be sure to discard the contents immediately, as some invaders can cause nasty odors!
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