The best-known species, Armadillidium vulgare, was introduced to New England in the early 19th century and has become widespread throughout North America.

[9] It may be triggered by stimuli such as vibrations or pressure, and is a key defense against predation; it may also reduce respiratory water losses.

The diet of pill bugs is largely made up of decaying or decomposed plant matter such as leaves, and to a lesser extent, wood fibers.

Pill bugs will also eat living plants, especially in wet conditions, sometimes consuming leaves, stems, shoots, roots, tubers, and fruits.

This diet has a secondary effect of decelerating the breakdown of litter, aiding in the retention of organic material in the soil.

Farmers in the United States and in Argentina have also reported increased rates of pill bugs destroying seed oil and soybean crops.