Learning Center

Identifying Spiders

About 3,000 species of spiders are found in the United States. Spiders rarely bite people, and most species found in the world are harmless. However, some people may be allergic to a spider’s bite, and a few species of spiders are known to produce bites that may have serious medical implications for humans. Two of the more medically important types are the black widow spiders, and the brown recluse spider and its relatives, which are rarely found in Maine.


Cellar Spiders

Appearance:

Color: Pale yellow to light brown or gray
Legs: 8
Shape: Long skinny legs with small body
Size: ¼-3/8”
Region: Found throughout the U.S.

General Information:

Cellar spiders are commonly referred to as “daddy-long-legs” because of their very long, thin legs. As their name implies, the spiders are found in dark and damp places. There are about 20 species of cellar spiders in the United States and Canada.

Habits:

Cellar spiders build loose, irregular, tangled webs in corners. They hang upside down on the underside of the web. The webs are not cleaned but instead a new web is continually added. This habit can result in extensive webbing in a relatively short time.

Habitat:

The spiders and their webs are usually found in dark and damp places, such as cellars, basements, and crawl spaces. They can also be found in the corners of garages, sheds, barns, and warehouses, on eaves, windows, and ceilings, and in closets, sink cabinets, and bath-traps. Cellar spiders seem to fare better in areas with higher relative humidity.

Risks:

Cellar spiders do not pose a threat to humans. While they are commonly found in homes, they usually stay in one place. They are not known to bite.

Prevention:

  • Seal cracks on the outside of the home, especially around doors and windows, and use screens to prevent entry into homes.
  • Using yellow light bulbs for exterior lighting may reduce the number of spiders and other insects, as they are typically attracted to white-light sources.
  • Lowering the humidity in basements, cellars and crawl spaces with the use of a dehumidifier or ventilation can discourage cellar spiders from living there.

House Spider

Common House SpiderAppearance:

Color: Yellowish brown, abdomen dirty white with a few dark spots (sometimes with a black triangular spot in the center) to almost black, with several dark stripes meeting at angle above tip of abdomen; legs
Legs: 8
Shape: Elongated abdomen
Size: 3/16-5/16” (female) 1/8-3/16” (male)
Region: Found throughout the U.S.

General Information:

This is usually the spider most often encountered indoors. It is a nuisance pest, probably more because of its webs than the spider itself. This spider is found worldwide and is common throughout the United States and Canada.

Habits:

The house spider randomly selects its web sites and creates a tangled web. If a web does not yield prey it is abandoned, another site is selected, and a new web is built. Survival is low in modern homes with low humidity and few insects, higher in garages, sheds, barns, warehouses, etc. because of more prey and generally higher humidity, and highest outdoors in protected places.

Habitat:

Inside structures, house spiders are most likely to be found in upper corners, under furniture, in closets, angles of window frames, basements, garages, and crawl spaces. Outside they are often around windows and under eaves especially near light sources which attract prey.

Risks:

House spiders are nuisance pests but pose no threats to humans.

Prevention:

  • Seal cracks and use screens on windows and doors.
  • Use a vacuum to remove adults, egg sacs and webs. If a broom is used, adults usually escape.

Black Widow Spiders

Appearance:

Color: Black, with characteristic red “hourglass” on back.
Legs: 8
Shape: Round
Size: 3/4” length; 3/8” diameter
Region: Found throughout the U.S.

General Information:

Black widow spiders are most recognized for the red hourglass shape under their abdomen. Male black widows are usually brown. Contrary to legend, female black widow spiders rarely devour the male black widow spider after mating.

Habits:

Black widow spiders spin their webs near ground level. They often build their webs in protected areas, such as in boxes and in firewood. Females suspend a cocoon in the web with hundreds of eggs. Spiderlings disperse soon after they leave their eggs, but the web remains. Black widow spiders also use their webs to ensnare their prey, which consists of flies, mosquitoes, grasshoppers, beetles, and caterpillars. Black widows are comb-footed spiders, which means they have bristles on their hind legs that they use to cover their prey with silk once it has been trapped.

Habitat:

Black widow spiders are often found around wood piles and gain entry into a structure when firewood is carried into a building. They are also found under eaves, in boxes, and other areas where they are undisturbed.

Risks:

The venom of a black widow spider is a neurotoxin and is used as a defense. Black widow spiders do not bite humans instinctively. The black widow spider bite can cause severe pain. Young children and the elderly are especially susceptible to a severe reaction to a black widow spider bite.

Prevention:

  • Avoid black widow spider bites by wearing heavy gloves when moving items stored for a long period of time.
  • Spiders often hide in shoes, so check shoes and shake them out before wearing.
  • When spider webs are visible, use caution before putting your hands or feet in that area.

Brown Recluse Spider

Appearance:

Color: Light to dark brown, with characteristic dark brown violin marking on back.
Legs: 8
Shape: Round
Size: 5/8″
Region: Found in the south central Midwest from Ohio to Nebraska and southward through Texas to Georgia.

General Information:

Brown recluse spiders or violin spiders have a characteristic dark brown violin marking on their back. Since the violin pattern is similar to the patterns on cellar spiders and pirate spiders, an examination of the eyes will help identify a brown recluse spider. Most spiders have eight eyes; recluse spiders have six eyes arranged in pairs with one median pair and two lateral pairs.  The abdomen of the brown recluse spider is covered in fine short hairs that, when viewed without magnification, give it the appearance of soft fur.

Habits:

Brown recluse spiders are nocturnal and eat other bugs like cockroaches and crickets. Male brown recluse spiders wander farther than females and will crawl into shoes or other clothing.

Habitat:

Brown recluse spiders often live outdoors in debris and wood piles. They can be found indoors in storage areas and dark recesses.

Risks:

Like the black widow spider, the brown recluse spider bites in defense and does not bite humans instinctively. They will bite humans when the clothing they are hiding in is worn. The brown recluse spider bite is painful and can produce an open, ulcerating sore.

Prevention:

  • Avoid keeping clothing on the floor.
  • Store clothing and shoes inside plastic containers, and shake out all clothing that has been in a hamper before wearing or washing.