Pseudoscorpions

Family: 
Various families in the order Pseudoscorpionida (pseudoscorpions), in the class Arachnida
Description: 

The largest of these tiny creatures only reach about ¼ inch long. The body is flattened and teardrop- or pear-shaped. The tip of the abdomen is rounded (not elongated into a stinger like that of a true scorpion). There are 8 walking legs, plus 2 very long, armlike pedipalps ending in pincers, much like the pincers of a scorpion. Body color varies but is usually black, brown, tan, yellowish or other muted colors. Some species lack eyes.

Size: 
Length (not including legs): to ¼ inch.
Habitat and conservation: 
Pseudoscorpions, usually found in leaf litter, humus, behind bark and under rocks, are a distinct order within the class Arachnida (arachnids). They occasionally are found within homes, where they arrive having hitched rides on houseflies and other flying insects. Some species live with mammals and birds, feeding on their lice and other parasites. They are often found in henhouses, where they feed on the lice chickens harbor.
Foods: 
Pseudoscorpions prey on a number of small insects, mites and larvae, which is why they sometimes survive in human homes—they eat booklice, clothes moths, dust mites, ants and more. There is a tiny venom gland in their pincers that is used to subdue their minute prey (they are harmless to humans and are simply too small to bite us). Then, they secrete a digestive fluid onto the prey and ingest the dissolved remains.
Distribution in Missouri: 
Statewide, though seldom seen or noticed.
Status: 
Various species are common throughout the state. Pseudoscorpions are in the class Arachnida (arachnids) along with spiders, mites and ticks, daddy longlegs, true scorpions and others. These are all different orders of arachnids, just as the grasshoppers, beetles, butterflies, true bugs and others are all different orders in the class Insecta (the insects).
Life cycle: 
Pseudoscorpions are known for their elaborate mating displays that end in a ritual where both partners lock pincers and dance around until the male pulls the female over a packet of sperm he has deposited on their “dance floor.” The female carries the eggs and the hatched young on her body. When molting, many species spin a small silken cocoon for shelter during that vulnerable time. Depending on species, pseudoscorpions can live for several years and spend 2–3 years as mature adults.
Human connections: 
Because they are harmless to humans, yet eat many pests such as the larvae of clothes moths and carpet beetles, plus ants, dust mites, small flies and booklice, pseudoscorpions are considered beneficial to humans.
Ecosystem connections: 
Food chains are better described as food webs, and pseudoscorpions fill an interesting position as a tiny predator of extremely minute insects and other invertebrates. In the world of mites and lice, pseudoscorpions are top predators, but in the larger view, they are only foundational.