Redbacked Jumping Spider

The Redbacked Jumping spider (Phidippus johnsoni) is one of the largest and most common jumping spiders in the western parts of North America. It is not to be mistaken for the highly venomous and unrelated Redback spider (Latrodectus hasselti). The Redbacked Jumping spider may inflict a painful bite in self defense if threatened, although there are not any serious medical consequences.

Adult Redbacked Jumping spiders are usually about 0.4 inches in length. Although the female has an additional black strip on her body, both males and females have bright red abdomens. Male and female Redbacked Jumping spiders have shining teal chelicerae. The rest of the spider’s body is mainly black. The Redbacked Jumping spider resembles a velvet ant in both its size and coloration.

The Redbacked Jumping spider can be found in southern Canada, the Pacific Ocean, the Great Plains and northern Mexico. This spider can be found from sea level to tree line, and is often found in dry places such as the oak woodlands or the coastal dunes. In 1976 a study found that there were between two and thirty Redbacked Jumping spiders found within 10,763 square feet.

Under rocks and wood on the ground this spider assembles a visible tubular nest. The Redbacked Jumping spider stays inside its nest at night and during bad weather. Egg laying, molting, sometimes courtship and mating take place inside the nest. Typically this spider eats prey half of its own size, it can range from 0.08 inches to 0.4 inches. Although the Redbacked Jumping spider preys heavily on other spiders it also feeds on insects such as flies, bugs, moths, and caterpillars. Cannibalism may occur periodically, generally with females feeding on the males.

This spider bites when threatened. Bites may result in pain and swelling at the location, which can last for several days.

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