Poisonous Spiders of Vermont

None of the common spider species found in Vermont gardens poses a life-threatening danger to humans, but the bite of one rare species can cause potentially serious harm. Other venomous spiders in the state may inflict painful bites, but healthy adults usually suffer no serious, long-term effects from them.

The black widow spider is most common in the southern United States where winters are warm, but its range extends well into New England, including the southern part of Vermont. The spider is rare in the state, however.

The female black widow is larger than the male. The female's body is about 1/2 long, and its legs spread to a width of about 1 1/2 inches; the male is about one-half the female's size. The female is black and shiny, and it typically has a red marking in the shape of an hourglass on its underside. The male, also black, usually has lighter-colored streaks along the sides of its abdomen.

The female black widow builds a web in a quiet, out-of-the-way spot, such as under dense foliage, in a woodpile, in a rock wall or on a fence. It stays in the web to guard egg cases, and it will bite to defend them or itself if threatened.

The bite of the female black widow can cause significant symptoms, including muscle cramping, high blood pressure, nausea and shortness of breath. In vulnerable individuals, such as young children and elderly people, reactions to the venom can be fatal.

The brown recluse spider is also a native of the warmer parts of the United States, and its natural habitat does not extend as far north as Vermont, where it is unlikely to be able to survive outdoors. Still, brown recluse bites have been diagnosed in Vermont and other places where the spider is considered to be rare or not to exist. Most of these cases are believed to be medical misdiagnoses and misidentifications of other spider species.

The brown recluse is a light- or medium-brown spider with a body length of about 3/8 inch and legs about 3/4 inch long. It often has a fiddle-shaped marking on its back, but the marking may be hard to spot on some specimens. Its most distinguishing features are its six eyes arranged in three pairs; most other spiders have eight eyes.

Brown recluses tend to hide in secluded locations, such as in woodpiles, under rocks and in outbuildings.

Species commonly mistaken for the brown recluse include grass spiders and sac spiders.

Prompt medical treatment is called for in the case of a suspected black widow bite. Immediately after the bite, the application of ice to the site can help to reduce swelling. Medical professionals will likely monitor a bite victim for signs of serious reaction, such as difficulty breathing or elevated blood pressure, and administer medication to control pain and swelling. In severe cases that don't respond to conventional treatment, antivenin may be administered.

Other spider bites may be treated with the application of ice and over-the-counter pain relievers. Seek medical attention if an open sore develops at the site of a bite, if any sign of infection is present or if whole-body symptoms such as fever develop.

Avoid being bitten by potentially dangerous spiders by using caution while you work in gardens and elsewhere on your property, and do what you can to discourage spiders from moving into your yard.

Wear protective clothing such as gloves, closed-toe shoes, a long-sleeved shirt and long pants when working near places where spiders may live, and don't stick your hands into potential spider habitats without looking.

Keep your garden and outbuildings as uncluttered as possible, and clean up brush and debris piles promptly to remove the places where spiders may hide.