Scorpions

We found the first scorpion in the house a few days after we arrived. I was in bed arranging books on the night table when I bumped the small, wooden lamp; a scorpion dashed out from beneath the base and disappeared over the back. I moved the night table, but the scorpion was gone. In the morning, we moved the furniture, but couldn't find it. A couple days later, Rande saw a scorpion on the wall in the bathroom similar to the one on the night table. I dispatched it with a fly swatter. Rande identified it on the Internet as a bark scorpion (Centruroides exilicauda). So far, we've found seven bark scorpions (five in the house) and two unidentified scorpions outside.

Bark scorpion about 2.5 inches total length on the wall in the living room

Unidentified scorpion about 3 inches total length outside the house

Sixty species of scorpions have been reported in Baja (Williams 1980). The bark scorpion is considered the most venomous in North America (link) and has several interesting traits that distinguish it from other scorpions – it can climb walls and ceilings, does not burrow like most scorpions and can occur in aggregates of 20-30.They grow to 3 inches and live 3-5 years. Females are viviparous (bear live young) and carry the young on their backs. They eats insects, like crickets, cockroaches and spiders (link), all of which inhabit our house. And they can squeeze through a crack as narrow as 1/16 of an inch (link).

Bark scorpions use their venom to immobilize and kill their prey. When disturbed or threatened by a human, they sting but don't always inject a full dose; it takes a couple weeks for scorpions to regenerate their venom (link). John Steinbeck in The Pearl (1947), which is set near La Paz, Baja California Sur, describes the symptoms of someone stung by a small, climbing scorpion, probably a bark scorpion:

…And all of these people knew about the scorpion. An adult might be very ill from the sting, but a baby could easily die from the poison. First, they knew, would come the swelling and fever and tightened throat, and then the cramps in the stomach…

If someone is stung by a scorpion, they are advised to wash the site with soap and water and apply a cold compress. If they are stung on an arm or leg, they should elevate it above the heart. Antihistamines and aspirin or ibuprofen are helpful. The young and the elderly are more likely to experience a severe reaction than healthy adults. Those who experience an allergic reaction are advised to seek medical attention immediately (link, link).

A note on taxonomy: the Arizona bark scorpion is common in the US Southwest. Williams (1980) considered the bark scorpion in Baja California synonymous with the bark scorpion in the US (link). Some researchers consider it a separate species, the Baja California bark scorpion (Centruroides exilicauda), closely related to the Arizona bark scorpion (C. sculpturatus) (link).

Williams, S. C. 1980. Scorpions of Baja California, Mexico, and adjacent islands. Occasional Papers of the California Academy of Sciences, No. 135, 127 pp.