The Q&A Archives: Pillbugs sowbugs

Question: We have had an explosion of pillbugs this winter/spring and they are all around the house and in the garage. What can we do get rid of them. We do have irrigation in front of the house for foundation plantings, but we've always had and we have not increased the watering time and this winter season I believe was drier than normal. Any ideas would be appreciated. Thank you.

Answer: Sowbugs are land crustaceans which look very similar to pillbugs, at least at first glance. Sowbugs are small crustaceans with oval bodies when viewed from above. Their back consists of a number of overlapping, articulating plates. They have 7 pairs of legs, and antennae which reach about half the body length. Most are slate gray in color, and may reach about 15 mm long and 8 mm wide.

The pillbug on the other hand has a rounder back, from side to side, and a deeper body, from back to legs. When disturbed, it frequently rolls into a tight ball, with its legs tucked inside, much like its larger but dissimilar counterpart the armadillo.

Sowbugs have gills which need constant moisture, so they tend to live in moister northwest climates. They are primarily nocturnal, and eat decaying leaf litter and vegetable matter. They may also feed on the tips of young plants, so can be considered pests, but they also help the environment by breaking up decaying plant matter and help speed up the recycling of the nutrients they contain.

In the spring and summer, these creatures sometimes migrate by the thousands, marching toward and into your house. No one knows for sure what causes these migrations. The best guess is that it's a combination of temperature and humidity. These critters like secluded damp areas where they can feed on decaying plant material. But too much or too little moisture in their environment can make them leave these areas in huge numbers.

When the rain falls, they emerge from the compost you've lovingly spread around your garden. For the most part, pill bugs are harmless and can even beneficial. They break down organic matter into smaller bits. The problems start when they start munching on seedings or a red ripe strawberry. Protect seedlings with a little diatomaceous earth or a bit of drinking straw split and wrapped around the stems.

Natural predators include frogs, newts, toads and small mammals which live and hunt at night in the moist areas where the Pill Bugs live. Sometimes as they moult, when they are still soft, they can be eaten by their own kind. Another main enemy is a spider which dispatches them with venom before devouring the contents of their body.

Removing plant debris to discourage them is all that is required in most gardens. But the valuable contribution they make to the decomposition process in vegetable matter means that unless they are a direct threat to seedlings or crops, they should be left well alone. In the commercial setting they can be controlled by soil sterilization with steam or methyl bromide .

You can also effectively trap pill bugs using a half of a cantaloupe that's placed upside down where pill bugs are a problem.

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