Royal Alberta Museum: Invertebrate Zoology - Bug Facts

[Caterpillars and Other Immature Insects]

Fact Sheets: Commonly Observed and Asked About Insects and Spiders Found in Alberta

Pseudoscorpion (Order Pseudoscorpiones)

Pseudoscorpion
Credit: Terry Thormin

INTRODUCTION

These curious little arthropods are arachnids and thus are relatives of the spiders and scorpions. They often get into houses where, if they are discovered, the owners are intrigued by them and want to know what they are.

IDENTIFICATION

Unlike insects, pseudoscorpions (and all arachnids) have eight legs. Pseudoscorpions do look somewhat like scorpions, but they lack the long tail with the bulbous stinger on the end. Body length of these creatures is about 3 to 4 mm.

DISTRIBUTION

Pseudoscorpions are found worldwide and there are about 2000 known species. There are probably fewer than half a dozen species of pseudoscorpions found in Alberta, and they are distributed throughout the province.

TIME OF YEAR

Pseudoscorpions hibernate through the winter and are active during the warm weather. I would suspect that individuals that establish territories indoors in unfinished basements could remain active through the winter.

HABITAT AND HABITS

Typically pseudoscorpions are found outdoors in leaf litter, under rocks, bark and logs, in mosses and in the soil. They also occasionally get into houses, and one cosmopolitan species, Chelifer cancroides, is typically found in houses. This is the species that is most often found indoors in Alberta. Because pseudoscorpions often turn up in clothes closets, I suspect that these are individuals that have been accidentally brought in on clothing. Another common location for them to be found is in bathtubs and sinks where they cannot escape up the smooth sides and are easily seen against the white enamel. All pseudoscorpions are predators and, when in a house, help keep populations of undesirable insects under control.

SIMILAR SPECIES

There are about 200 species of pseudoscorpions in North America, and probably less than six in Alberta. Trying to identify these to species is a real challenge that we are not going to attempt here. The comments under identification will help you separate them from scorpions.

COMMENTS

Most people are just interested in knowing what these creatures are, although occasionally someone may express concern. Pseudoscorpions do not have the stinger that scorpions have and are not in any way dangerous. They do have poison glands though, that open up in the claws of the pedipalps. This poison is only used to subdue their prey.

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Last update: August 29 2008