Crab Spiders

Facts, Identification and Control

Latin Name

Family Thomisidae

Appearance

Crab spiders belong to the Family Thomisidaeand are named for their crablike appearance and movements. Crab spiders have two large, strong front legs that are used to grasp prey. They scuttle sideways with their hind legs, although some species do move like other spiders.

Crab Spider Illustration
Crab Spider

Behavior, Diet & Habits

Instead of spinning webs to catch prey, crab spiders utilize camouflage. Some crab spiders resemble bird droppings, while others look like fruits, leaves, grass, or flowers. Some crab spiders are capable of changing colors entirely.

When prey approaches, the crab spider attacks and administers a poisonous bite. Crab spider venom is potent enough to render large insects immobile. It is not medically threatening to humans.

Reproduction

Crab spiders produce eggs within a few weeks after mating. These eggs are deposited into two silken egg sacs, which are joined at the center. However, their eggs are not housed within a web. Females commonly remain near egg sacs in order to protect their young from predators. Hatching time depends on environmental conditions. After spiderlings emerge, they resemble adults. These small spiders undergo a series of molts before becoming mature and fertile.

Signs of a Crab Spider Infestation

Crab spiders excel at not being seen. When detected it is the spider itself that would be the sign. Crab spiders typically would not infest indoors and would prefer to remain outside.

Flower Crab Spiders (Family Thomisidae)

Giant Crab Spider (Olios giganteus)