My son found a strange little bug in the basement that looked kind of like a tick but it had claws like a crab. When he brought it into school, his biology teacher said it was a pseudoscorpion. What is that? How did it get into our basement, and does it sting? E. H.,

The name and the appearance of these little guys can scare people. They’re tough-looking (under a magnifying glass!), but harmless. We don’t see them in homes very often, their actual habitat is outdoors in damp, dark areas like leaf litter, mulch, or moss, or under bark or stones. Because they like moisture, when they do accidentally get inside they usually end up in damper parts of a home like basements, bathrooms, or laundry rooms. Sometimes they are found in a sink or drain.

Pseudoscorpions are sometimes called “false scorpions.” They have pincer-like claws like scorpions, but do not have the long ”tail” with a stinger at the tip that scorpions have. They’re much smaller than scorpions, only about 1/5-inch long, and are transparent to yellowish-brown in color with darker claws.

Pseudoscorpions are not insects, they have 8 legs instead of 6, so they are related to spiders, ticks, and mites. In fact, as you know, they are sometimes mistaken for ticks since they are similar in size and shape. Like spiders, they have silk glands and use silk to cover their egg sacs and the cocoons where they spend the winter.

Pseudoscorpions Feed on Small Insects and Arachnids

In homes, these little arachnids are actually beneficial predators on small pests like springtails, book lice, clothes moth larvae, mites, and spiders. They are also sometimes called “book scorpions” when they are found hiding in books, probably to feed on book lice also found there. They grab their prey with their claws and inject a paralyzing poison from the tip of the claw. Their claws are too small and their poison too weak to hurt people. We usually see only one or two pseudoscorpions at a time in a building. When there are more, it often means that there is an infestation of small insects or spiders that the pseudoscorpions are feeding on.

Photo Credit : “Pseudoscorpion” by Richard Avery | CC0 via Wikimedia Commons.