Hackledmesh Weaver Spiders
Amaurobius and Callobius species
The Amaurobiidae superficially resemble the previous spiders, the funnel weavers, in the family Agelenidae. In fact, two genera in Agelenidae, Coras and Wadotes , have recently been transferred to the amaurobiids, bringing the number of genera in this family to thirteen.
Amaurobiidae have eight eyes that are similar in size, are typically of light (or white) color, and are arranged in two rows. The females range from 5 to 14 millimeters in length and the males from 5 to 12.5 millimeters. The carapace is a reddish, mahogany brown, darkest at the front in the region of the eyes and the chelicerae. The legs are lighter in color than the carapace. The abdomen is generally gray, although the background color varies from a pinkish flesh color to a dark, charcoal gray. A pattern of lighter areas or spots (which sometimes run together) can produce a larger, lighter central area. It is common to have chevron-type lighter areas on the posterior portion of the abdomen.
The web is an irregular “mesh” with an ill-defined tube retreat in the areas previously described.
Callobius and Amaurobius species have similar life histories and behaviors. They are most often found in damp locations under bark, leaf litter, and stones, as well as in woodpiles and other protected areas.
The males overwinter as immature spiders, molt twice the following spring, and become adults in April. They die after mating. The females have been found during all seasons, indicating that they probably live for at least two years. The egg sacs are deposited in the same locations that the spiders are found—often in the webs. The numbers of eggs found in the cocoons range from 73 to 175.
These spiders are frequently found in damp basements and other areas of the home in the autumn. However, there are few indications that these spiders will readily bite or that the bites are medically important. The one verified record of a bite by an immature Callobius species resulted in pain, itching, swelling, redness, and nausea.
Authored by: Steve Jacobs, Sr. Extension Associate
March 2002 Revised 2015
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