Sow Bugs

Sow Bug, Pill Bug or Potato Bug - Woodlice

Common Names

Aarmadillo Bug, Boat-Builder, cheesy bug, doodlebug, pill bug, potato bug, roly-poly, sow bug, roll up bug, chuggypig, chucky pig or wood bug.

Potato Bug and it's life

These insects have shell-like exoskeleton which is shed as they transition through life stages. The moulting happens in two stages. First the back half is shed and then two to three days later the front half is shed. This moulting process is different from that of most other arthropods. Most arthropods shed their exoskeleton in a single transition.


A sowbug (Trachelipus rathkei) at left and a pillbug (Armadillidium vulgare) on right with inset showing pillbug rolled up in defense posture.


Sow Bug or Pill Bug

Not more than 3/4 inch long; thorax composed of seven hard overlapping plates with seven pairs of legs; only pillbugs are able to roll up into a ball for protection, when distrubed.
Both sowbugs and pillbugs are terrestrial members of the crustacean group Isopoda, more closely related to crabs and shrimp than to insects. Most isopods are aquatic or marine, and many are parasites of fish. Characteristically isopods have seven pairs of legs and the body consists of a head, with antennae, and a series of armored body plates, ending in a tail-like telson.

Habits & Diet:

Prefer moist locations; found under objects on damp ground; mostly nocturnal; sometimes found in basements and ground levels of structures.
Sowbugs and pillbugs are major pests in gardens, nurseries and glasshouses along the Coast and other areas of high rainfall or fog drip. They feed on decayed vegetable matter and tender young plant growth, attacking young plants of all kinds, including strawberries, vegetables, forage crops and even mushrooms.
They are nocturnal and are most active during the rainy season, or in damp foggy conditions.


Both sowbugs and pill bugs mate throughout the year, with most activity in the spring. The female carries the eggs, numbering from 7 to 200, in a brood pouch on the underside of her body. Eggs hatch in three to seven weeks and the young are white-colored. They remain in the brood pouch for six to eight weeks until they are able to take care of themselves. There may be one to two generations per year, with individuals living up to three years depending on weather conditions.

Other Information:

Armadillidium, the pillbug, is actually an introduced pest species from Europe. Controlling these creatures is difficult and generally involves eliminating damp, dark places where they can shelter, and the use of pesticides.

Pest Significance:

These pests have been known to feed on cultivated plants, such as ripening strawberries and tender seedlings. Woodlice can also invade homes en masse in search of moisture and their presence can indicate dampness problems.