Pseudoscorpions are tiny arachnids that are easy to identify because of the enormous pincers on the front of the body. They are common outdoors but because of their small size (approximately 1/8th inch) they are easy to overlook and usually go unnoticed. When they are noticed is when they accidentally invade homes and wander into sight. They are not a household pest because they cannot bite or sting and they do not attack the house structure, furniture or occupants. They may be an annoying curiosity, usually during the spring and summer, as an occasional "accidental invader."
Pseudoscorpions have 8 legs and are closely related to mites, ticks and spiders. The pincers (called pedipalps) give them a strong resemblance to the true scorpions. Scorpions, however, are always much larger and have a sting on the end of their abdomens.
Natural habitats for pseudoscorpions include under leaf litter and mulch, in moss, under stones and beneath tree bark. They have also been reported in bird nests and between siding boards of buildings. Because they are sometimes found among books, they are also known as "book scorpions."
Pseudoscorpions are predaceous and therefore beneficial. They feed on other arthropods, particularly small insects and mites.
Special treatments for control of pseudoscorpions are usually not warranted. Offending invaders need only be picked or swept up and discarded back outdoors.
This article originally appeared in the May 24, 1996 issue, p. 85.