Sow Bug vs. Pill Bug
Sow bugs are land crustaceans, which look very similar to pill bugs, at least at first glance. Sow bugs are small crustaceans with oval bodies when viewed from above. Their back consists of a number of overlapping, articulating plates. They have seven pairs of legs, and antennae which reach about half the body length. Most are slate gray in colour, and may reach about 15mm long and 8mm wide.
The pill bug 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.
Sow bugs 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.
The presence of sow bugs or pill bugs in the living quarters of a home is an indication of high-moisture conditions. This condition will also contribute to a number of other problems including mildew, wood rot and a good breeding environment for other insects. Reduce moisture or humidity level indoors. Use bathroom fans, stove hood vent fans, vent clothes dryers outside. Crawl spaces and attics need to be well ventilated. Remove excess vegetation and debris around exterior perimeter of the home. Make sure that leaf debris (leaves hold moisture and hide the bugs) is cleaned up from around the outside of your house. Keep rain gutters and downspouts clean and in good repair. Instead of chemicals, use a caulking gun to close any cracks or crevices at or near ground level.
Houses built on a concrete slab poured directly on the ground, can have more of a problem with sow bugs or pill bugs if there is no moisture barrier under the concrete. Built-in planters are usually a bad idea for many reasons. Window box planters and planter boxes on decks tight against the house are good breeding places for many bugs. Make sure all your doors (ground level, to the outside) are weather-stripped. If your garage is attached or integral with the house, make sure those doors are properly weather-stripped also. Watch for obvious moisture problems in the garage and bottom level. Keep soil levels well below structural wood around the home.