House pseudoscorpion

Description

House pseudoscorpions are small, exotic, predacious arachnids. They are highly synanthropic, meaning they thrive in habitats associated with humans, and they are the pseudoscorpions most commonly encountered by humans. They are most often reported in houses, barns, stables, chicken coops, bee hives, and other human-built structures. They are sometimes found in sinks or bathtubs, where they went in search of water but were unable to climb up the slippery sides to get out. They feed on a variety of small invertebrates, including mites, booklice, and fruit flies.

House pseudoscorpions are believed to be native to Europe and parts of Asia. They were introduced into North America accidentally. As the first Europeans came to the new world, they brought with them books, paper goods, hay, straw, agricultural goods, and firewood. Pseudoscorpions, feeding on pests like booklice, mites, and carpet beetle larvae, were likely transported along with the people and goods.

House pseudoscorpions are now cosmopolitan, occurring on all continents worldwide except Antarctica. They are commonly recorded in Europe, North Africa, Central Asia, and North America, but there are very few records in other regions. They occur throughout most of the United States and southern Canada, but they are absent from the Deep South, the Great Plains, and the Great Basin.

Adults are small, ⅛″ (3 to 4 mm) in length. The body is pear shaped, flattened, and reddish brown.

The front part of the body (cephalothorax) has distinct lateral keels. The surface is granular, and there are numerous large granules scattered among the smaller ones. There are two eyes. The last part of the jaws (chelicera), called the hand, has a granular surface and 4 long, bristle-like hairs (setae). The pedipalps are very long and have pincer-like claws (chelae) at the tip. The chelae have a fixed finger and a movable finger. Both fingers are untoothed, and both have a small but well-developed venom apparatus at the tip.

The rear part of the body (abdomen) has 12 segments but only 10 segments are visible. The upper part of each segment (tergite) is clearly defined. On males, tergites 1 through 4 or 5 have distinct lateral keels.

All of the legs have 6 segments. The third segment (femur) on the first and second pair of legs are a different shape than those on the third and fourth pairs. On all legs, the last segment (tarsus) is undivided, and it has a pair of claws at the tip. The claws are split (bifid) on all legs except for the front legs of the male. On the fourth pair of legs, the claws have an accessory tooth. On the male, the tarsus on the first pair of legs does not have a spine at the tip.

Size

Total Length: ⅛″ (3 to 4 mm)

Similar Species

Habitat

Houses, barns, stables, chicken coops, bee hives, and other human-built structures

Ecology

Season

Year round

Behavior

Life Cycle

Food

Small invertebrates