Fall's Unwelcome Guests

Steve Allgeier
Carroll County Master Gardener Program

Many of the common and less desirable "house visitors" are starting to show back up in Carroll County homes these past couple weeks. No, I am not talking about your Mother- in- Law either, but smaller and less mundane critters such as bugs and mice. Here is a quick rundown:


Leading the pack of unwanted visitors are the "basement worms" or millipedes. These critters are actually not worms, but a very small crustacean (1 - 1.5 inches long) with many short legs. They will not harm you or your property. Typically, they enter homes and garages during the fall and aggravate homeowners by curling up and dieing in large numbers. Millipedes live outdoors where they feed on decaying organic material such as wood mulches and plants.

Fixing doors and windows so that they fit tighter, especially the ones near ground level, can discourage these pests. Vacuuming up the few that make it into the house is an easy an effective way of dealing with the balance that have evaded your improvements to the leaky doors and windows.

Multicolored Asian lady beetle (MALB):

Multicolored Asian Ladybird Beetles or MALB are commonly found entering and congregating in area homes beginning in the fall. Once inside they occasionally appear inside the house especially on warm days around windows. These beetles can be distinguished from our native ladybugs by observing the area directly behind their head. In this area, there is a small has a black "M" shaped marking on a white background.

They were introduced to the United States to help reduce pests on and agricultural crops and ornamental plants and have proven to be a very effective biological control agent. Marylanders have been seeing them since the late 80's. However, this ladybug has proven to be a nuisance pest because it tends to over winter in houses and other buildings, sometimes in extremely large numbers. They generally hibernate through most of the winter in cool dark isolated areas, but have been known to come out and congregate on the inside of sunny windows during warmer days. These insects may become quite a nuisance in the house, especially if they emerge in large numbers. They release an orangish liquid when disturbed, that smells bad and can stain walls or fabric. This ladybug is also known to nip people (yes they have an irritating little bite for many people).

Again, control is best done through exclusion. This can be a little more involved, because they frequently don't enter just around doors and windows, but are also likely to work their way around exterior trim, shingles, cracks in the foundation, and gaps near rooflines. If they do make it inside, the vacuum may become your next best management tool. For people that have a real problem with massive numbers of MALB's then you may want to try a new black light trap developed by the US Dept. of Agriculture.


Mice have never fallen out of style. They seem to show up every year invited or not. Unfortunately, the control options pretty much remain the same: traps, baits or a cat. Actually, if you are not a cat person or the cat you have is not a good mouser, there are still plenty of effective strategies for reducing the number of mice that come inside to over winter.

If you have had consistent seasonal problems with mice in the past, then control measures should be taken prior to the mice showing up. Creating physical barriers best does this. Too often this aspect of rodent control is neglected. To exclude mice you need to seal all openings ¼ inch or larger with a heavy material that will resist mouse gnawing (hardware cloth, sheet-metal, concrete or mortar…).

Beware of the new mouse deterrents or scaring devices that emit a sound or light that is said to discourage mice. There is little evidence to suggest that house mice respond to these devises.

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