What Are Bugs That Look Like Crabs?

While many bugs may bear a passing resemblance to crabs, pseudoscorpions look very similar to the pincer-armed crustaceans. Pseudoscorpions are arachnids, related to scorpions, whip scorpions, ticks and spiders. Despite having very small venom glands in their pincers, pseudoscorpions are completely harmless to humans, and the Penn State College of Agricultural Sciences discourages the use of pesticides to control their numbers.

Pseudoscorpions are very small animals, whose bodies are less than one-fifth of an inch in length. When their pincers are extended, they span about a third of an inch. Their teardrop-shaped bodies feature 12-segmented abdomens and small cephalothoraxes. Pseudoscorpions have two eyes, eight legs and two pincers that they use to capture food.

Pseudoscorpions inhabit humid habitats, such as damp leaf litter, caves and inside rotting logs. However, they often invade residences, particularly if the humidity inside the house is high. Very small insects and other invertebrates form the prey base for pseudoscorpions. Book lice, clothes moths, ants and mites are some of their common prey.

Pseudoscorpions have elaborate mating rituals. When a female enters the territory of the male, he will grab her by the pincers and move with her. He deposits a spermatophore on the ground and eventually moves her into position to pick it up. The entire process may take an hour or more to complete.