Roly-polies serve a purpose, but sometimes they can be pests
Whether you think of them as pill bugs, armadillo bugs, slaters or roly-polies, you can find these interesting creatures pretty much anywhere you go in the world.
Children especially seem to be fascinated by them. When my son, Geoffrey, was quite small, we’d find them in his pants pockets after he’d gone to bed. The dead ones. The live ones had already crawled out and would be spotted scurrying across his bedroom floor.
At least a couple of times a year, I’m contacted about pill bugs by concerned housewives or gardeners. To begin with, roly-polies aren’t insects. They’re land-living crustaceans distantly related to shrimp. They rely on gills to breathe and, because of that, have to have sufficient humidity to keep them breathing.
Most pill bugs can’t last too long inside our manmade caves. The humidity is just too low. As a rule, they’ll be dead in a couple of days once they manage to get inside. If you can’t wait that long, you can use their defensive tactic against them. Roly-polies get their name from their ability to roll themselves into tight balls. This process, called conglobation, is a defense against predators. Just roll them up and sweep them out the door.
In our gardens, pill bugs can be an occasional pest. They spend most of the time eating decaying plants and animals. They’re Mama Nature’s waste disposal crew. Sometimes, for some unknown reason, they’ll attack seedlings (and ripe strawberries). Their preference is toward members of the melon, bean and cabbage families. Once the plants acquire sufficient size, the pill bugs leave them alone.
Growing your plants in pots or over some sort of structure that keeps the fruit off the ground reduces the likelihood that any damage will occur. If the numbers are just too many, you can make traps from a hollowed-out orange or melon. Place the cored-out fruit upside down in your garden. The pill bugs are attracted by both the scent of the decaying fruit and the super-moist environment. Remove it the next morning and dispose of the contents. Keep this up until the numbers are at a level you can tolerate or at the point where your plants are well established.
You also can start your plants with collars. Use an old cardboard tube sunk into the soil around the seedling. This will form a barrier, keeping the pill bugs from getting to the tender plant.
Finally, since I have a little more space left and I’m a fount of trivial information, I’m going to give you a few interesting facts about these small creatures. Pill bugs are true blue bloods. Their blood contains copper instead of iron. When exposed to oxygen, it turns blue. They don’t urinate. They turn their liquid waste into ammonia gas, which passes directly through their exoskeleton. They eat their own poop. Don’t go “yuck.” Those cute little bunny rabbits do the same thing for the same reason. Each time a roly-poly (or rabbit) defecates, it loses some important nutrients. To optimally recycle these resources, a pill bug will consume its own waste, a practice called coprophagy.
And last, but not least, male pill bugs are superfluous. Female roly-polies can reproduce quite well without them. It’s a process called parthenogenesis.
That’s your lesson for today. I hope to have something interesting for you next week as well.
Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. To have him answer your individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi, MS 39535.
