Sowbugs And Pillbugs In The House: Why They Keep Turning Up Dead

Sowbugs and pillbugs are crustaceans that live in damp ground outside and walk in at ground level. They breathe through gills, they dry out fast in a heated house, and most of the ones found indoors are dead or dying within a day or two. A steady supply of them points at water held against the foundation.

The Stark County version of this is a handful of grey, armored, segmented things along a basement wall or just inside the garage door, a few of them curled into tight balls. Late October is when people notice. A wet autumn keeps the soil at the foundation saturated, the first cold nights move everything at ground level toward a warm wall, and the ones that make it inside end up somewhere you walk barefoot.

They Are Not Insects, And That Explains The Rest

Count the legs and the answer stops being an insect. Washington State University Extension says sowbugs and pillbugs are not insects but crustaceans, more closely related to crabs and shrimp. The University of Kentucky describes them as isopods, crustaceans that manage to live on land, and University of Florida IFAS Extension calls them the only crustaceans that have adapted completely to terrestrial habitats. They carry seven pairs of legs, against the three pairs that define an insect.

How they breathe is the part that matters indoors. NC State Extension says they breathe by means of gills and live under vegetable debris and other objects lying on damp ground. Gills need moisture to work at all, so an animal built this way cannot spend long on dry concrete with the furnace running. Very few of them get more than a room from the door they came through.

Pillbug Or Sowbug? Poke It And See

Touch it with a pen. University of Florida IFAS Extension puts the difference plainly: a pillbug can roll into a ball and a sowbug cannot. What stops the sowbug is a pair of tail appendages called uropods that stick out past the last segment, where a pillbug has a smooth rounded rear end and nothing visible but its antennae. The University of Kentucky adds the reason pillbugs bother to roll at all. It is not only defense. It holds water in.

Why Most Of Them Are Dead By Morning

The house is too dry for them. The University of Kentucky says indoor insecticide applications are typically of little use against pillbugs and sowbugs, because they usually die from lack of moisture indoors anyway. Colorado State University Extension goes further: control is rarely necessary, and where it is required it should primarily involve moisture control, because these arthropods are susceptible to drying.

They are also not doing anything to the house while they are in it. University of Missouri Extension says sowbugs and pillbugs do not pose an economic or health threat to humans, and University of Florida IFAS Extension says that although they occasionally wander indoors, they do not cause damage. The complaint is the sight of them. Washington State University Extension lists the indoor response as physical removal, which means a vacuum, a broom, or carrying them back outside.

A Steady Supply Means Standing Water

One or two after a heavy rain is weather. The same corner producing them every day through the autumn is a drainage report. University of Missouri Extension describes where they live outdoors as moist ground at the soil surface in mulched flowerbeds, leaf litter, grass clippings and other debris around foundations, and names the way in as cracks between slabs and porches and openings in basement walls. The useful question is not how to kill them. It is what keeps that strip of ground wet.

• A downspout that discharges at the wall instead of out past the drip line.
• Grading that slopes back toward the house, so every rain parks water against the block.
• A window well with a blocked drain, which holds a shallow pond that things fall into and cannot climb out of.
• Sprinklers or a soaker hose running near a doorway. The University of California Statewide IPM Program specifically advises keeping irrigation water back from foundations, especially near entranceways.
• Mulch, leaf litter and grass clippings banked against the siding, which the University of Kentucky names as the harborage worth removing first.
• A dripping hose bib, a sweating pipe or a crawl space vent that keeps one patch of soil damp after the rest of the yard has dried out.

Why There Are So Many Of Them Out There

The numbers come out of a brood pouch. University of Florida IFAS Extension describes the female carrying her eggs in a marsupium on the underside of her body, with anywhere from 7 to 200 eggs in a brood, hatching in three to seven weeks, and the young staying in the pouch another six or seven weeks after that. NC State Extension puts a typical brood at about 50 young. University of Missouri Extension says females produce one or two broods a year and that the young take roughly a year to reach adult size.

They last, too. University of Florida IFAS Extension says individuals may live to two years, and both NC State Extension and Oklahoma State University put the upper end at three. A mulch bed nobody has turned over in a few seasons is holding overlapping generations rather than a single hatch, which is why pulling the habitat back does more than anything you can do at the door.

What Actually Keeps Them Out

Work it from the yard inward. Sweeping a basement floor while the mulch bed stays soaked is a chore you get to repeat every week.

• Pull the harborage off the foundation. The University of Kentucky says removing leaves, mulch, rotting wood, stones and flowerpots close to entrances and the foundation may greatly reduce unwanted visitors.
• Fix the drainage. The same source puts good drainage around the foundation at the center of keeping those areas dry.
• Move the water away. UC IPM advises keeping compost and mulch back from plants and building foundations and keeping irrigation back from foundations near entranceways.
• Close the gaps at ground level. Washington State University Extension lists decreasing or eliminating the space under door thresholds and securing windows, particularly basement windows, and their screens. UC IPM names weather stripping and door sweeps as the bottom barriers that matter.
• Seal the structural openings Missouri names: the cracks between slabs and porches, and the gaps in basement walls.

The One Place They Do Real Damage

Outdoors, in a vegetable bed. The University of California Statewide IPM Program says pillbugs and sowbugs occasionally feed on seedlings, new roots, lower leaves, and fruit or vegetables touching the soil, and Utah State University Extension says they sometimes become numerous enough to damage roots, seedlings, foliage and produce sitting on the ground. The remedy is the same remedy, applied to the bed. UC IPM recommends reducing decaying organic matter on the soil, keeping the soil surface drier, watering less often where the plants can tolerate it, and watering early so surfaces are dry by evening. It adds that raised beds, plastic mulch and drip or furrow irrigation usually keep them from becoming a serious problem at all.

When Is It Worth Having Someone Look?

Not for the sowbugs on their own. Colorado State University Extension is right that control is rarely necessary, and a treatment aimed at isopods is aimed at the wrong thing. It is worth a call when the same wet strip around the foundation is also turning out millipedes and centipedes and silverfish and earwigs, because that is one condition showing up as several different complaints, and the perimeter and entry work that settles it is the same work either way. Our State Shield Essential plan covers spiders, millipedes, centipedes and the rest of the seasonal invaders on four visits a year, and our occasional invader library page covers the others that share the same damp ground.

If the same bugs keep appearing in the same corner week after week in North Canton or anywhere across Stark, Summit, Portage, Wayne and Tuscarawas counties, the perimeter and the entry points are worth a look before winter. Ask for a free estimate through our request form or call 330-494-6199.