Common Name: Sowbugs, pillbugs
Scientific Name: Varies
Description: Adults grow to about 3/8 inch long, have a number of rounded body segments and seven pairs of legs. Sowbugs possess a pair of tail-like structures on the back end of the body. Pillbugs do not have these structures and are capable of rolling into a tight ball when disturbed, a behavior that resulted in their common name, “roly-polies.”
Isopoda (sowbugs and pillbugs) are terrestrial crustaceans, and are more closely related to lobsters, shrimp and crayfish. They even have gills. One saltwater isopod, Ligia exotica, occurs along the Texas seashore among jetty rocks and pilings. They are active in the evening and run rapidly, superficially resembling cockroaches in form and behavior. They are called “sea roaches” and occasionally enter structures near the waterline. Another group of crustaceans, Order Amphipoda, occurs in salt and fresh water habitats. One freshwater amphipod species, Hyalella azteca, builds up in large numbers in temporary ponds and puddles. When their aquatic habitats dry up they leave in search of other bodies of water and occasionally invade homes and structures, hopping about. Members of this species are commonly called “scud.“ They are about 1/4 inch long, grayish to pinkish and shrimp-like in form. Crayfish (also called crawdads), shrimp, crabs and lobsters belong to the Order Decopoda. They have a shield (carapace) that covers the thorax and have five pairs of legs, the first of which have a large claw. Texas crayfish are poorly known, with five species occurring in Brazos County.
Life Cycle: Females lay eggs that they carry in a pouch underneath the body. Eggs hatch into young sowbugs and pillbugs that resemble adults but are smaller. They remain in the pouch up to 2 months after hatching. Development to adults occurs in about a year and they breed mainly in the spring. They may live up to 3 years. Up to three broods may be produced annually.
Habitat, Food Source(s), Damage: Mouthparts are for chewing and rasping. Sowbugs and pillbugs spend bright daylight hours in damp dark habitats such as underneath stones, logs, leaf litter and other debris. At night they venture out and feed on decomposing organic material, including mulch and grass clippings. They will feed on the tender foliage, stems and roots of young garden vegetable transplants, seedlings and bedding plants. They also rasp the outer skin of cucumbers laying on the ground in gardens, causing fruit to be deformed and blemished.
Pest Status: Mainly a nuisance, particularly when they venture indoors; capable of feeding on tender plant tissue and occasionally causing considerable damage to garden transplants and seedlings; medically harmless.
Management: See Managing Insect and Mite Pests in Vegetable Gardens. See also Vegetable IPM.
Literature: Brook et al. 1982; Drees & Wicksten 1990.