Millipedes, Centipedes, Sowbugs, and Pillbugs

Occasionally millipedes, sowbugs, pillbugs and centipedes may be found in moist areas of the home, in rotting wood, or under piles of moist debris in basements, near patio doors and in garages. None of them are true insects; they belong to the class Crustacea, a closely related group of arthropods. Centipedes, sowbugs, pillbugs, and millipedes are all primarily nocturnal, avoiding light.

Millipedes

Millipedes ("thousand leggers") have elongated, segmented, worm-like bodies with short antennae and two pairs of short legs on each body segment. Species that commonly invade homes are usually ½ to 1½ inch long and brown or black. They crawl slowly across the ground and roll themselves into a coil when disturbed.

Habits: Millipedes normally live outdoors but may become nuisance pests indoors by their presence. At certain times of the year (usually late summer and autumn), due to excessive rainfall or even drought, a few or hundreds or more leave the soil and crawl into houses and basements. Annoying populations accumulating in swimming pools have been reported as early as late June. Fall migrations during rainy and cool weather may result as a natural urge to seek hibernation quarters. Millipedes do not bite humans nor damage structures, household possessions or foods. Occasionally, millipedes attack stems and roots of young plants, or they may feed on tubers or vegetables stored in cellars or basements. However, millipedes customarily feed on decaying vegetation. They can give off a disagreeable odor and if crushed, leave an unsightly mess.

Control Measures: In order to discourage millepedes it is important to keep the house and outside area as dry as possible. Siince they prefer moist, decaying organic matter and shade, always keep compost piles, grass clippings, rotting wood, leaf piles, plant debris, stones, etc. away from the house foundation. Also, ivy beds and mulch near the house may become a favored habitat. Rake and remove trash or leaf litter in a strip three feet wide surrounding the house foundation if practical, exposing the soil surface to drying from the air and sunlight. Repair and seal cracks and openings in the foundation wall and around  door and window frames with caulking compound and weather stripping. Ventilate basements and subfloor crawl spaces to eliminate excess moisture. Indoors, many will die of desiccation (drying out) and can be collected by broom and dustpan, vacuum cleaner, or other means and discarded.

Insecticides: Outdoors, spray a protective barrier thoroughly soaking the soil in a 5 – 15 foot band around the house. Also, thoroughly spray the sides of the house up to the level of the first story windows, especially across doorways and other openings. The carbamate insecticides, such as carbaryl (Sevin), give the fastest knockdown. Wettable powder formulations provide the best soil residual control. Treatment of peat moss, mulch, wood chips, leaves, etc. used in landscaping around the house is important. Subsequent water sprinkling will carry the insecticide down into the soil where these creatures hide. Do not expect immediate kill since control may be slow (three to six days or more). There are many products available for outdoor use; check with a local garden center and always read the label and follow directions and safety precautions.

Centipedes

Centipedes ("hundred-leggers") are reddish-brown, flattened, and elongated with many segments, most of which have 1 pair of legs. The actual body length is an inch or slightly longer (wormlike), surrounded with 15 pairs of very long legs making the creature appear much larger. The first pair of legs is modified into poisonous jaws located below the mouth. Centipedes are predaceous, feeding on insects, spiders and other small animals. They do not cause damage to plants.

The house centipede is grayish-yellow. The actual body length is an inch or slightly longer. The last pair of legs is more than twice the body length of the female. Unlike most other centipedes that normally live outdoors, it can live indoors especially in damp, moist basements, cellars, bathrooms, crawlspaces or unexcavated areas under the house. They are sometimes seen running rapidly across the floor with great speed, stopping suddenly to remain motionless and then resuming fast movements, occasionally directly toward the homeowner in an attempt to conceal themselves in their clothing. They have a "fearful" appearance but cause no damage to the structure, household possessions, or foods. Some can bite when handled carelessly, resulting in a slight swelling or pain no worse than a mild bee sting.

Control Measures: Centipedes require moist habitats and areas of high humidity so it is important to keep the house and outside area as dry as possible. Keep old boards, or rotting wood, compost piles, grass clippings, leaves, stones, etc. away from the house foundation. Remove, if practical, trash or leaf litter in a strip 3 feet wide surrounding the house foundation, exposing the soil surface to drying from the air and sunlight. Repair and seal cracks and openings in the foundation wall and around door and window frames with caulking compound and weather stripping. Properly ventilate basements and subfloor crawlspaces to eliminate excess moisture. Indoors, control nuisance insect populations to reduce the food source (prey) of centipedes. These creatures can be collected by broom and dustpan, vacuum cleaner, or other means and discarded. Centipedes may be killed by squashing with a gloved hand (remember, they can bite) or any makeshift "swatter."

Insecticides: Try to locate the infested area or cause of infestation (nearby woods, pastures, lakesides,river areas atc). Outdoors, throughly soak the soil in 5 – 15 foot band around the house. Also, throughly spray the sides of the house up to the level of the first story windows, especially across doorways and other openings. The carbamate insecticides, such as carbaryl (Sevin) give the fastest knockdown. There are many products available for outdoor use; check with a local garden center and always read the label and follow directions and safety precautions.

Sowbugs and Pillbugs

Sowbugs and pillbugs, sometimes called "woodlice," are oval, dark-gray, hard-shelled arthropods with seven pairs  of legs. They reach about ½ inch in length. Pillbugs can roll themselves into a ball when disturbed but sowbugs cannot. Sowbugs and pillbugs live outdoors but they may occasionally enter homes in damp areas such as basements, first floor levels, and garages. These creatures are a nuisance by their presence; they do not bite humans nor damage structures or household possessions. However, if present in large numbers, they can feed on young plants in greenhouses. Some may crawl into swimming pools and drown, causing complaints. Those that wander into homes usually die in a few days unless they find a moist place near a leaky pipe or in a damp basement, bathroom, or laundryroom.

Control Measures: Since sowbugs and pillbugs require moisture to survive, it is important to keep the house and outside as dry as possible. Remove hiding places, such as piles of leaves, grass clippings, mulch in flower beds, fallen fruit, pet droppings, boxes,boards, stones and other debris from the foundation walls, doors, basement windows and other points of entry. Properly ventilate basements and subfloor crawl spaces; he use of fans and dehumidifiers will help dry out the basement and other damp rooms. Repair and seal cracks and openings in the foundation wall, around doors, and around basement windows with caulking compound and weather stripping. Drain standing water and moist areas near potential points of entry. These creatures can be collected with a broom and dustpan, vacuum cleaner or other means and discarded.

Insecticides: Outdoors, treat the soil in a 3 – 6 foot band around the foundation walls, especially damp areas, surrounding the house and even underneath crawl spaces, at doorways, window wells, and other potential entry sites. It is helpful to rake mulch, leaves, etc.away from the house foundation before treatment. The carbamate insecticides, such as carbaryl (Sevin), give the fastest knockdown. There are many products available for outdoor use; check with a local garden center and always read the label and follow directions and safety precautions.

Adapted from the Cornell Cooperative Extension and the Purdue University Cooperative Extension Service, 1999; Ohio State University Extension