Funnelweb Spiders

INTRODUCTION & CLARIFICATION

The funnel weaver spiders in the family Agelenidae, which are found in the United States, are often confused with funnelweb spiders that are found in Australia. The important differences between the two are:

  • The United States funnel weaver spiders are not considered medically important to people.
  • The funnelweb spider commonly referred to as the Sydney funnelweb spider in found Australia, is a serious medically important spider.
  • The medically important Sydney funnel-web spiders (Atrax robustus) are in the spider family Hexathelidae, are not naturally found in the United States and are not related to our Agelenidae funnel weaver spiders.

SCIENTIFIC NAME

Family Agelenidae

APPEARANCE

There are many species of funnel weaver spiders found in the United States; therefore the range of appearances of this family of spiders varies a great deal. However, generally these spiders range in body size (not including the span of their legs) from about 1/5 of an inch to about ¾ of an inch. Coloration is generally brownish or grayish and their legs and other body parts are hairy and often have bands and markings that are darker in color. Some of the most commonly seen funnel weaver spiders have a long, tail-like structure that extends from the rear end of the body. This structure is used for spinning their webs. When disturbed, these spiders typically run in a quick, darting manner.

Webs

Other than their physical appearance, the funnel weavers can be identified by the appearance of their webs. Funnel weaver webs are very distinctive and generally have a horizontal, flat surface for capturing prey, plus a small funnel shaped tube that leads to a silk burrow that functions as a protective hiding place. When prey fall onto the horizontal web, the spider quickly moves out of the “funnel”, grabs its prey and then carries it back to the “funnel” to eat its meal.

Funnel Web Illustration
Funnel Web

BEHAVIOR, DIET & HABITAT

Individual funnel weavers sometimes accidentally wander into homes when plant watering or other disturbances flush the spiders from their webs. Mature males may unintentionally enter the home when searching for mates. Sometimes, funnel weavers build webs in cluttered basements and crawlspaces inhabited with small crawling insect prey.

Sources of food are primarily insects, although some funnel weavers may cannibalize other funnel weaver spiders. Spider experts think this could simply involve the fact that since these spiders are often in such close proximity to each other they may wander onto each others’ webs and becoming a victim.

Funnel weavers commonly build webs in tall grass, stacks of wood, dense shrubs, and between rocks. The spiders may also be found in man-made structures like barns and sheds, which may be inhabited with prey. These spiders may also build their webs in abandoned burrows of various small animals. In addition, some of the funnel weaver spiders may build their webs on wood shakes and vinyl siding, porch eaves and bricks with cracked/broken mortar near a light source that attracts insects. Regardless of the web’s location, these spiders must have some sort of gap or recess into which they can build their “funnel” retreat.

REPRODUCTION

As soon as males reach sexual maturity, they begin wandering the environment in search of mates. After finding a female and mating several times, a male funnel weaver soon dies off. Females remain by their webs their entire lives and only tend to leave to find new locations to build webs. Not known to seek out mates, female funnel weavers wait for wandering males to find them. Most of the female’s time is spent capturing or feeding on prey in order build the strength necessary for mating and egg production. After producing eggs and hiding the egg sac in a crevice, the female dies.

SIGNS OF A FUNNEL WEAVER SPIDER INFESTATION

The appearance of the horizontal webs on the surface of vegetation or structures is the most obvious sign of funnel weaver spiders.

DISTRIBUTION

Various species of funnel weavers can be found throughout North America, including remote areas such as Alaska and Hawaii.

MORE INFORMATION

These spiders are meek and non-aggressive and do not bite unless threatened, provoked or sense there is no way to escape without putting up a defense. The majority of funnel weaver spider bites occur when working in the garden, removing or cleaning up a woodpile, cleaning up clutter in a basement or outside shed, or startling an unseen spider. Bites from funnel weavers are not medically important and at worst are comparable to a bee sting. At one point, it was thought the hobo spider (Eratigena agrestis), a funnel weaver, was a medically important spider. However current research, observations and medical literature do not support this prior thinking. Further evidence is provided by the fact the hobo spider is often the most common spider found in homes within Europe, where it also is considered harmless to humans.

Prevention of spiders begins with making sure the population of insects that serves as food for spiders is kept to a minimum and that holes, cracks and gaps in the home’s doors, windows and foundation are properly sealed to prevent entrance into the home’s living space. In addition, removing ground litter that serves as harborage for spiders is also helpful. Should the homeowner need assistance in control of these or any other spiders, contact your pest management professional (PMP) and request an inspection. Your PMP can then use his inspection findings to prepare a comprehensive pest management plan that will effectively and efficiently deal with the specific pest problem. His recommendations will also include using a vacuum to remove webs and spiders and precautions to be sure to remove and discard vacuum cleaner bags to prevent reinfestations.

Trapdoor Spiders vs. Funnelweb Spiders

Because both arachnids reside in burrows and exhibit similar behaviors, funnel web spiders and trapdoor spiders are often confused. Males of both species leave their homes to hunt for potential mates, while females remain in the burrow or web and wait for prey. Female funnel web and trapdoor spiders are capable of laying hundreds of eggs at a time.

The trapdoor spider’s burrow is equipped with a covering which closes when prey enters. Funnel web spider webs are narrower at one end than the other and do not feature coverings. Rather, the silk strands that comprise the funnel web spider’s burrow vibrate to indicate the presence of prey. Upon this alert, the funnel web spider emerges to attack.