Natural Life of the Lost Coast: California forest scorpions and pseudoscorpions: not as scary as they look


By Eve Broughton

Although finding a scorpion in your woodpile may startle you, it may only be an imposter, the pseudoscorpion, both of which make their homes here in the Lost Coast Region of Northern California. I found a scorpion on the floor of my dining room the other night. It must have hitched a ride inside with the firewood. Since it was upside down, I figured it was dead, a victim of my faithful feline friends.

While the cats are courageous, the scorpions are not. When threatened, they hide their faces with their pincers and play dead. That didn’t work for this scorpion. Running away is the second strategy of defense. Rarely do they sting, and the venom is not dangerous with only mild effects, but the sting does hurt.

Both the scorpion, Uroctonus mordax, and the pseudoscorpion are arthropods, meaning an invertebrate animal with an external skeleton, segmented body, and jointed appendages; both are in the class of Arachnida, but in different order.

The scorpion is a forest dweller, native to northern California, western Oregon, and southern Washington. They prefer humid settings, and probably burrow during hot, dry weather. Around here, I’ve seen them most often under pieces of wood on the ground, or lurking beneath the bark of firewood. They are night-hunters, and use their pincers to seize the prey (spider or large insect), and their poisonous stinger to kill it.

Males can be distinguished from females (when you have them both to compare) because the males are duller. (No comment.) You Tube has interesting videos of scorpions seeking mates and mating. The couples join pincers and “dance.” The female can give birth to a brood of 26 pale, miniature scorpions. This usually happens in August, September or October. They hang around Mom, riding on her back, for two weeks. At 10 days of age, the young undergo their first molt, and begin to forage on their own. Five molts and two years later, they reach maturity. The California Forest Scorpion may live as long as four to six years.

Pseudoscorpions may resemble scorpions, in having large pincers, but are more closely related to spiders. They have a rounded abdomen and no tail and no stinger. They do have poison glands, but these are in the movable “finger” of the pincer. This poison is used to inactivate the prey, which includes small insects such as springtails, flies, ants, moths, beetle larvae, and mites. Are they to be feared? No. They are small, less than one-quarter of an inch and not aggressive.

Most species have simple eyes, some don’t. This makes sense, as the habitat for pseudoscorpions is often in forests, lurking among moss or under loose bark, leaves or stones. They are active in the warm months.

Like spiders, they have silk glands, but these are on the jaws and are used to spin cocoons, in which they mate, molt, or over-winter. It may take the young several years to mature, and adults live up to four years.

So be curious, not frightened, the next time you see one. And if you go exploring at night, take a black light: scorpions will glow blue under its ultraviolet rays.

Whitethorn resident, Eve Broughton is a biologist, nature enthusiast and a board member of the Lost Coast Interpretive Association

This article is part of a series about Natural Life of the Lost Coast, a project of the Lost Coast Interpretive Association. If you are interested in contributing an article to this bi-weekly column about the plants, animals and human history of the Lost Coast Region, contact Cathy Miller at

photo caption:


This scorpion was found inside a Southern Humboldt residence.

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