By Betsy Matos
Iowa State University Extension
Approximately 100,000 arachnid species have been described. Arachnids, better known as spiders, ticks, mites, scorpions and pseudoscorpions are close relatives to insects. Arachnids have eight legs, two body regions and no antennae. Insects have six legs, three body regions, and one pair of antennae.
Commonly found in yards and gardens, Pseudoscorpions are small arachnids -- 1/16 to 1/8 inch. Similar to true scorpions, they have large pincer like claws, but lack the long tail and stinger. Their body color ranges from yellowish-tan to dark brown and they may have anywhere from zero to four eyes.
There are more than 3,000 species of Pseudoscorpions in the world. Usually active throughout the spring, summer and fall months, they construct silk chambers to overwinter. Spending most of their lives inside crevices, they like to live under mulch, leaf litter, stones and tree bark. It is common for Pseudoscorpions to “hitch-hike” on other animals indoors to settle in moist places such as sinks, bathtubs and drains.
Pseudoscorpions do not mate like other arthropods. Males and females do not have to be in physical contact with each other for mating to occur. Males and females act completely separately. The process begins by the male depositing a spermatophore, a packet of sperm. The female then actively searches for the spermatophore. When she finds it, she moves her body over the spermatophore and takes up the sperm, leaving the empty sac behind. Females will only care for the young for a short period, having only one brood per year with fewer than two dozen young.
Inside their pincer-like claws is a poisonous gland that opens at the end. They inject the poison to subdue the prey. Since they are extra-oral digesters -- meaning that they digest their food before consuming it -- they must inject digestive fluids through a tear in the body wall of the prey and later absorb the digested contents.
Pseudoscorpions are predaceous, feeding on other arthropods, particularly small insects and mites; therefore, they are beneficial indoors as well as outdoors. They aggressively feed on cloth moth larvae, carpet beetle larvae, booklice, ants, mites and small flies. Outdoors, Pseudoscorpions will feed on small animals living in the upper layers of the soil.
Humans have nothing to fear from these small creatures that are good for our gardens and our homes.