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Pseudoscorpions

Quick facts

  • Pseudoscorpions (book scorpions) are related to spiders, ticks, mites and scorpions.
  • They lack the stinger that true scorpions have.
  • They are not common indoors and are NOT harmful to people.
  • They like high humidity and are found in leaf litter, moss, under tree bark and stones, in bird and mammal nests, and in buildings.
  • Pseudoscorpions are mostly commonly seen during spring and summer when it is warm.
  • Pesticides are NOT necessary or recommended.

Also known as false scorpions, there are over 3,300 species known in the world and about 200 species in North America. 

How to identify pseuodoscorpions

A yellowish brown pseudoscorpion with two long pincers on its head
Typical pseudoscorpion. Note the pincer-like pedipalps.

They are arachnids and have oval or teardrop shaped, flattened bodies with two pedipalps (pincers).

  • They are reddish or brown.
  • They are small and have a body length of about 1/5 inch long (about 3/8 inch long when the pedipalps are extended).

When they walk, they often appear crab-like and can move as quickly backward as they move forward.

  • Without their large pincers, pseudoscorpions look like ticks.
  • They are similar to scorpions but lack the long ‘tail’ and stinger that scorpions have.

Behavior and habits

Pseudoscorpions live in many habitats and are often found in cracks, crevices and similar spaces.

They enter homes by hitching rides on larger insects (e.g. flies and beetles) or on firewood, and are usually found in damp areas, such as laundry rooms, basements and bathrooms.

What do pseudodcorpions eat

Pseudoscorpions feed on many types of small insects and other arthropods, including springtails, psocids (barklice and booklice), thrips, beetle larvae, flies, ants and mites.

  • Many aggressively stalk their prey while others prefer to hide and ambush insects.

  • They have poor vision and use sensory hairs on their pincers to find prey.

  • When a small insect brushes against these sensory hairs, the pseudoscorpion seizes the insect.

  • Poison glands in the pseudoscorpion pincers help to paralyze prey.

  • They inject saliva into the victim and then feed on the liquefied contents.

Pseudoscorpions usually live two to three years. There may be one or two generations in a year.

Are pseudoscorpions dangerous?

A black oval shaped pseudoscorpion with two long pincers on the head
Pseudoscorpions look fierce but are harmless to people
  • Pseudoscorpions are harmless to people and pets.
  • They cannot bite or sting.
  • The poison gland used for feeding is NOT harmful to humans or pets.
  • They are not destructive to food, clothes or property.

How to protect your home from pseudoscorpions

Generally, you should not see more than a few pseudoscorpions indoors.

  • Physical removal is the only necessary control.
  • If possible, slide a piece of paper underneath them and release them outdoors.

It is not common to find large numbers of pseudoscorpions, but if you do:

  • Control pseudoscorpions by drying out damp areas with fans or dehumidifiers.
  • Make sure a vent fan is installed and used while taking showers/baths in the bathroom.
  • Contact a pest management company to check if the crawlspace in your home is dry and has adequate ventilation.
  • Check along the roofline for poor attic ventilation, trees overgrowing the roof or leaf litter in the eaves. Correct any of these conditions if they are found.

Jeffrey Hahn, Extension entomologist and Stephen Kells, Extension entomologist

Reviewed in 2018

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