Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu
Something I do not see very often is sow bugs or pill bugs or roly-polys (Fig. 1) feeding on and damaging vegetables, in this case it was turnip and radish bulbs. Sow bugs are brown to gray and a half inch in length. Because they breathe through gills that need to be kept moist they are limited as to their ability to move to drier areas and have the tendency to cluster in dark moist areas during the day and feed at night. They are attracted to thick mulch or rich wet soils or decomposing compost piles.
At times tender foliage and roots of young vegetables can be on their menu when their populations are large, and the environment is wet. Sow bugs rarely cause much damage in the field, but in small densely grown areas of bulbs such as radish or turnips they can feed on the outer layers of the bulb (Fig. 2).
Sow bugs are difficult to control with just chemicals. It is better to eliminate their hiding places or alter their environment. Some ways to accomplish this is by removing any mulch from around plants or by improving drainage or by decreasing watering frequency if the ground is constantly moist. If sow bugs are still doing damage after efforts of altering their environment fail, a bait can be used which contains spinosad and iron phosphate.
Figure 1. Sow bugs in wet soil feeding on a turnip bulb
Figure 2. Sow bug damage to turnip bulb