Some strange bugs have suddenly appeared in the under-sink cabinet in our laundry room, and in a back storage room in our basement. They’re light gray and very tiny, but they jump. There must be a hundred of them under the sink. Do you know where they came from? How do we get rid of them? P. K., Manchester, NH

Springtails (Entomobrya unostrigata)

You should have an exterminator identify these pests, but I think they might be springtails, also called Collembola. These small insects are associated with areas of excess moisture where they feed on mold. They’re very common outside but almost never noticed.

I believe you’ve had a lot of rain recently in Manchester, so things are probably pretty damp outside. It’s no doubt damper than usual inside your home, too, since we’re at that time of the year when people are no longer using their air conditioner but really haven’t turned on the heat much. In other words, indoor humidity can be high right now, with no air circulation to dry things out. These are ideal conditions for springtails.

Springtails can move inside from their outdoor hiding places in mulch, soil, and damp wood — if those places get too wet or too dry. They’re so tiny that it doesn’t take much of an opening to let them in. Usually they die pretty soon in drier indoor air, but if they can find an area that is damp enough and has mold growth, their numbers can build up pretty quickly (see Springtails in Damp Areas).

Dry Things Out to Keep Springtails Out

Since springtails need moisture and humidity to survive, the key to their control is to dry out the areas where they are found. Hopefully the extra moisture in your basement level is temporary and will disappear once things get drier outside, and after you’ve turned on the heat in your home. If you want to speed up the drying process, you can also turn on your house fan, or use a portable fan, dehumidifier, or small space heater to dry out the places where you have found springtails. Wipe down the areas where you’ve noticed springtails with a mild bleach solution to kill any mold, then be sure to dry thoroughly. Check for a plumbing leak in that under-sink cabinet; that’s a common springtail infestation site.

If you’ve had this problem before, you will probably have it again unless you change the conditions that attract springtails (see Help For a Perpetual Springtail Problem). Repair plumbing leaks, window leaks, and fix condensation problems that are keeping areas wet. To reduce the springtail population around the perimeter of your home, you can cut back on heavy mulch and have an exterminator treat around the foundation of your home. Colonial can do that (see Our Preventative Maintenance Program Keeps Pests Away Year Round). Give us a call!

Photo: Joseph Berger, Bugwood.org