BLACK WIDOW SPIDERS
TECHNICAL BULLETIN Bulletin No. 518 July 10, 2007 The black widow spider is one of the most feared spiders, and rightfully so. While the males do not bite, the female's bite is poisonous to humans, and the reactions can be extremely painful. Fortunately, black widow bites are not usually deadly, especially if an adult is bitten, because they inject only a small amount of venom. PRIMARY IDENTIFIERS: Color: Shiny black Adult female markings: Red “hourglass” on underside Male and juveniles: Red or yellow bands and spots Legs: 8 Shape: Round Body Size: ½ to ¾ inch long (males are smaller)
Spread: 1½ inches Biology There are several species of black widows. The most common female black widow spider is shiny black, usually with two red triangles that meet to form an “hourglass” shape on the underside of her spherical abdomen. Her body is ½ to ¾ inches long. With legs extended, it has about a 1½ inch spread. Adult males are about half the female’s size, with smaller bodies but longer legs. Newly hatched spiderlings are predominately white or yellowish-white, gradually acquiring more black and varying amounts of red and white with each molt. Adult males and juveniles often have yellow and red bands and spots over their back. Habits and Habitat Black widows are shy and nocturnal in habit, usually staying hidden in their irregularly shaped webs,hanging belly upward. They normally build their web fairly close to the ground. Although not aggressive, and not instinctively inclined to bite, a female black widow may attack when her web is disturbed, particularly when guarding her egg mass. They are also prone to attack if disturbedwhen trapped in clothing or shoes. While the female is known to eat the male after mating (hence the “widow” moniker), this actually does not happen as often as commonly believed. Black widows can be found in all 50 states and southern areas of Canada. They like piles of wood and debris, barbeque grills, the underside of ledges, rocks, and plants and just about any sheltered place outdoors where its irregular mesh web can be spun. Cold weather and drought may drive them into buildings. WARNING! be established. Take proper precautions - wear gloves and pay attention to where you are working Be very careful when working around areas where black widow spiders may Control While black widows are resistant to many insecticides, they can often be controlled by simply removing allmaterials where they might hide and knocking down webs and destroying their tan egg sacs. Hazards The venom of the female black widow is a neurotoxin, used to paralyze and destroy its prey. Only the females bite is poisonous to humans; males and immatures (spiderlings and juveniles) are harmless. Even the female’s bite itself is often not painful and may initially go unnoticed. But the poison injected can cause abdominal pain similar to appendicitis, as well as pain to muscles, or strangely, the soles of the feet. Other symptoms include alternating salivation and dry-mouth, paralysis of the diaphragm, profuse sweating and swollen eyelids. Young children and the elderly are especially susceptible to a severe reaction to a black widow spider bite. Persons with heart conditions or other health problems may require a hospital stay. Heart and lung failure can result in death in rare cases. A physician can evaluate the severity of the bite, and give specific treatment to relieve pain if necessary. Healthy people recover rapidly in two to five days. First Aid Apply an ice pack over the bite location and keep the affected limb elevated to about heart level. Try to collect the spider specimen in a small jar or plastic bag, even if crushed or only partial segments, for examination by a spider expert if needed. If any reactions occur, treatment in a medical facility may be necessary. Call a Poison Center (800-222-1222) for additional directions.BLACK WIDOW SPIDERS
