Fact Sheets - Spiders
Pest Management Fact Sheet #5046
James F. Dill, Pest Management Specialist
Clay A. Kirby, Insect Diagnostician
Description & Biology
Spiders have been the subject of negative publicity for years. Their secretive nature, way of moving, and predatory nature make them common villains in folklore and popular media. Fear of a few highly poisonous spiders, such as black widow and brown recluse spiders, has expanded to include all spiders. Fortunately, black widows and brown recluse spiders are not native to Maine. Spiders can be considered to be beneficial when they feed on household and garden insect pests. It is unfortunate that many incidents of unknown skin irritation are attributed to spider bites.
Spiders have two body regions (a fused head and thorax [the cephalothorax] and an abdomen) as well as 8 legs. They are relatives of insects which have 3 body regions (head, thorax and abdomen) and 6 legs. Spiders spin silk which can be used to make webs for holding eggs, securing prey, or transportation. Some spiders wait for prey to get caught in their webs while others actually hunt for prey. Chance encounters with spiders or their webbing in unlikely places can render them a nuisance. Some spiders may bite in self-defense when carelessly handled or accidentally trapped.
Types of spiders occasionally encountered in the home include wolf, parson, fisher, jumping and house spiders. Wolf and fisher spiders tend to be large, hairy and fast. These tend to wander into houses from the outdoors. Fisher (Fishing) spiders are common along lakes, rivers and marshes and can actually feed on small fish and tadpoles. Parson spiders are hunters that are hairy and black with a white distinctive pattern on the abdomen. Jumping spiders, which are also hairy, are smaller and more compact, often moving in short quick starts. House spiders are generally not hairy and they have long spindly legs which are responsible for the formation of cobwebs. They are usually stationary and associated with their webbing.
Spider problems can be avoided or lessened by sanitation and exclusion. Clearing out basement clutter (including wood piles) eliminates harborage. Moving outdoor wood piles away from the house also helps. Window and door screens should be intact and tight fitting. Cracks and crevices in the foundation and siding should be sealed or caulked to prevent entrance of spiders.
Humidity should be lowered, if possible, in basements and crawl spaces. Using dimmer or yellow porch lights will cut down on the number of flying insects accumulating around the lights thus reducing the numbers of spiders feeding on them.
Spiders and webs can be removed by frequent dusting, sweeping, or vacuuming in corners, under furniture, behind pictures and other hiding places. Any undisturbed area may harbor spiders. Since spiders eat insects, eliminating household insects will help cut down spider numbers. As a last resort, household formulations of materials such as resmethrin, permethrin, bifenthrin, cyfluthrin, deltamethrin, tetramethrin, or pyrethrins sprayed in cracks and crevices and in corners (floor & ceiling) of rooms may be used to control both spiders and the insects they eat.
When Using Pesticides
ALWAYS FOLLOW LABEL DIRECTIONS!
Pest Management Office
491 College Avenue, Orono, ME 04473-1295
1-800-287-0279 (in Maine)
Information in this publication is provided purely for educational purposes. No responsibility is assumed for any problems associated with the use of products or services mentioned. No endorsement of products or companies is intended, nor is criticism of unnamed products or companies implied.
Published and distributed in furtherance of Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the state of Maine and the U.S. Department of Agriculture cooperating. Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.
Call 800-287-0274 or TDD 800-287-8957 (in Maine), or 207-581-3188, for information on publications and program offerings from University of Maine Cooperative Extension, or visit extension.umaine.edu.