Origin:
Like the Domestic house spider this species was believed to be native to Europe, but new evidence suggests that it has long been a native of western Canada and now has moved into the Pacific Northwest of the U.S. as well, where it is common in and around homes. It appears to be moving eastward and now can be found in Colorado, Montana, and Wyoming and west to the Pacific Coast of Oregon, Washington, and British Columbia.
Biology:
This species of funnel weaver has suffered from some terrible misconceptions, the first being that its Latin name of “agrestis” means “aggressive”. It does not, and instead agrestis is Latin for “rural”, meaning it is found most often in fields. It is a very NON-aggressive spider that prefers to retreat from threats and hide from human activity. It also has the legend built around it that it is the cause of severe necrotic lesions when it bites, and the most recent and unbiased studies on this in 2011 conclude that the bite is of no medical consequence, does not cause necrotic lesions, and does not transfer other bacteria or pathogens to human skin that may cause these reactions. They create wide, dense webs over low vegetation and clutter, using a hollow tube or “funnel” below the web as their resting area. When prey is detected on the web above they rush out to grab, subdue, and eat the prey, which will be insects and other small arthropods. Females create one to four egg cases, each with 50-100 eggs, and then die in the late fall. The egg cases are attached to the underside of objects and new spiders hatch in the spring.
Identification:
Typical of this genus will be a “herring-bone” pattern of dark stripes on the top of the abdomen. There are also 2 dark stripes running down the top of the thorax, but these various darker markings may also occur on other unrelated spiders. The spiders are brown, have long legs, and tend to lay fairly flattened. They have 8 eyes, with 6 of the eyes enlarged and facing forward to maximize their vision for spotting prey. Confirmation of the specific identification must be done by an expert.
Characteristicts Important to Control:
Indoors the spiders and their webs may be removed with a vacuum cleaner. When the webs are found on plants outdoors the ideal response is to leave them alone and to enjoy them. They are feeding on other unwanted insects and are highly beneficial. If necessary due to customer pressure the plants may be treated with a labeled insecticide for short term relief from the spiders and the web removed with a stream of water.
