Roly polies were a great source of entertainment for kids before video games and Pokémon came along. They have a much more impressive scientific name that does not sound nearly as interesting – Armadillidium vulgare. They are a familiar inhabitant of mulched areas and flower beds. Usually I get a few calls every fall, depending on the weather, from gardeners freshening up their mulched areas in their landscape. I have always called them "roly polies" because of their habit of rolling up into a tight ball when disturbed. Another common name is pillbugs because when they roll into a tight ball they look like a little gray pill.
Pillbugs are small, brownish to gray-black in color, and armored in appearance much like an armadillo. (Credit: Joseph Berger, Bugwood.org)
Pillbugs are small, brownish to gray-black in color, and armored in appearance much like an armadillo (hence, the scientific name Armadillidium … which reminds me of a joke. Question: Why did the chicken cross the road? Answer: To show the armadillo it could be done.)
But I digress.
In most years, pillbugs are content feeding harmlessly on decaying organic matter in and on the soil. They love the excess moisture we sometimes get in the fall that provides a perfect environment for their reproduction. Wet weather provides a good environment for pillbugs to become a pest on some landscape plants. Most feeding takes place in the evening or at night – the sneaky devils. Feeding pillbugs readily chew on small garden plants, and new transplants can be eaten to the ground overnight. Some of the plants attacked include hosta, pansies, blue lobelia, cardinal flower, English primrose, alyssum, zinnia, verbena and daisy. Garden vegetables and strawberries are also susceptible. During the day, pillbugs can be found in moist areas under mulch or leaves and vegetable debris of all kinds. Cooler portions of compost piles can also harbor large numbers of pillbugs. They are very prolific, giving birth to 30-80 young per brood. In Alabama, pillbugs may produce two to three generations per year. Adult pillbugs are relatively long-lived, with some surviving several years.
The best way to eliminate pillbugs is to destroy their breeding and hiding sites. Do not apply mulch too thickly around plants. A 2- to 3-inch layer is adequate.
This is a very important practice even if you don’t have a pillbug problem. Excessively thick mulch leads to plants producing roots in the decaying mulch rather than in the native soil. If you have excessive root growth in the mulch to the detriment of roots growing in the soil, your landscape plants will have a hard time surviving a drought because the mulch dries much faster than the soil.
Another simple way to reduce pillbug habitat is to get containers off the ground. Flower pots, planters, dog houses, firewood, bricks or other objects sitting directly on the ground should be elevated to allow air-flow and drying underneath. If you irrigate your lawn, you can likely turn the system off for the winter unless you grow a cool-season grass or just sodded a new lawn. However, during the growing season when you are irrigating, adjust the system so the soil around your home has a chance to dry between watering or, better yet, don’t allow the sprinkler system to water the shrub beds. Shrub beds should be irrigated with drip irrigation or micro sprinklers on a much less frequent schedule than turf grass once they are well-established.
When abundant, pillbugs may enter homes and become a nuisance. This can be prevented by careful sealing of doors and cracks in foundations. Pillbugs are harmless and can be removed by hand or by vacuuming. They rarely survive more than one or two days indoors, due to lack of moisture. Kittens like to play with them, but I doubt they offer much control.
Pesticide sprays are not normally needed, but can be used if the problem becomes severe. For more information and a list of chemical control options, visit http://citybugs.tamu.edu/ and search by the keyword "pillbugs."