Although most spiders possess venom glands, most are too small to break the skin with their fangs and have no desire to do so. All spiders will bite in self-defense if they are handled carelessly, such as being squeezed. Most bites occur when people roll over in bed on one and get bitten or when they put on their clothes and a spider inside the clothing bites when it is pressed against the skin. I am not saying all spiders are harmless. Black widows are certainly capable of producing a serious bite and any such bite by this spider should be considered a major medical emergency. The brown recluse is also dangerously venomous. Sac spiders and wolf spiders can give serious, though not fatal bites, particularly if you are allergic to any of the components of the venom. Daddy longlegs (aka harvestmen) are not at all dangerous despite their reputation to the contrary. Jumping spiders are interesting to watch but are not dangerous although a large one can bite if mishandled. Most of the small hunting spiders, such as ground spiders are incapable of hurting anyone.
There are three main species in the black widow group. The eastern black widow (Latrodectus mactans), the western black widow (Latrodectus hesperus) and the brown widow (Latrodectus geometricus). The eastern black widow is found throughout the east with the exception of Maine, New Hampshire and most of Vermont. The western black widow is found in every state west of central North Dakota south to Texas. The brown widow is found in Florida and Texas and may be expanding into neighboring states. All the female widow spiders have a reddish hourglass-shaped marking on the underside of a shiny black abdomen. The abdomen is brown in the brown widow. Medical: The black widow is feared everywhere although it isn't as dangerous as we are told. The toxic venom is neurotoxic, but the spider injects very little material and the death rate is about 1%. Additionally, the black widow is not inclined to bite unless it is squeezed or defending its egg sac in a web.
The false black widow is often mistaken for the real black widow. They are about the same size and the same color. The false black widow does not have the red hourglass marking on its abdomen. It usually has a yellowish band across the front portion of its abdomen on top. It originally came from Europe and is found along both coasts, the states that border the Great Lakes and has been found in Colorado, Arizona and New Mexico as well as a few other inland states. It is absolutely harmless and like the real black widow, it is very timid and non-aggressive.
The brown recluse spider (Loxosceles reclusa) is shy, sedentary and builds an irregular web that is often not even recognized as a spiderweb. It has a fiddle-shaped pattern on its cephalothorax. Females lay eggs in flattened egg sacs that are frequently attached to the underside of objects. When they are indoors, they can usually be found in dark places, beneath or behind furniture, in boxes or storage areas, among stored books and papers and similar areas. Outside they live under rocks, boards and other dark areas.
The natural habitat of the brown recluse includes the underside of rocks, loose bark, and crevices in decaying logs. The brown recluse is found from eastern areas of the country west to Texas, Oklahoma and eastern New Mexico. It is frequently transported to different areas of the country in luggage or by commercial vehicles. One species introduced into California and Massachusetts, Loxosceles laeta, is potentially dangerous. It occasionally comes to the United States in products shipped from South America. Medical: Brown Recluse bites are not painful at the time of the bite. After an hour or so there may be intense pain where bitten. There is usually a dark depressed area at the site of the bite which will turn darker in a day or so. The dead tissue will slough away and the bite area will scar over. Death seldom if ever occurs, but the bite is extremely debilitating and traumatic. If you know you were bitten by a brown recluse, seek medical attention right away.
This may be one of the most common spiders found in homes in the country. It is found in every state, most Canadian provinces and virtually all over the world. The cephalothorax (section where legs are attached) is shiny brown with two longitudinal stripes running down the middle. The abdomen is grayish with a series of chevron shaped markings running down the middle to the end. The legs are brownish-gray with black bands. The common house spider is harmless and feeds on a lot of household pest insects, so can be considered beneficial.
Ground spiders (family Gnaphosidae) are very common and are frequently found indoors. They live under debris on the ground outside and often accidentally wander into homes. Most of them are completely harmless. One species, eastern parson spider (Herpyllus ecclesiasticus), can give a painful, but not a dangerous bite. Some people suffer allergic reactions to the bite. This spider is about ½ inch long, blackish with a distinctive white or pink pattern on the middle of its back. The marking resembles an old-style cravat worn by clergy in the 18th century. This spider is found almost everywhere east of the Rocky Mountains. A very similar species, the western parson spider (Herpyllus propinquus) is found west of the mountains.
Sac spiders are responsible for spider bites in homes more often than most other species. They have a cytotoxic venom, which is the same as the brown recluse, although it isn't as toxic. It is possible many sac spider bites are blamed on the recluse. Two species are referred to as yellow sac spiders due to their similar coloration. They are Cheiracanthium inclusum and C. mildei. They are light yellowish to a pale yellowish-green, sometimes with an orange-brown stripe on top of the abdomen. They are small, ¼ to 3/8 inches long. Yellow sac spiders are found throughout the country.
Female sac spiders build a silken tube or sac in a protected area, often under furniture. They usually come out at night to hunt and that is when most bites take place. Usually the bite results in a sharp pain, but some people won't feel anything. It is rarely no more painful than a bee sting, but some people can have a bad reaction to it.
Jumping spiders are easily distinguished from other spiders by their four big eyes on the face and four smaller eyes on top of the head. Around the world there are probably more than 5,000 species of jumping spiders. In the U. S. there are at least 40 genera and more than 300 species.
Jumping spiders are charming spiders that look up and watch you. Their excellent vision allows them to hunt and spot their prey from long distances, creeping up then pouncing using their jumping ability.
The most important species of jumping spiders is probably Phidippus audax because it can be mistaken for the Black Widow. These spiders are 1/8" - 3/4" long with robust, relatively short legs, are mostly black with white or red markings on the dorsal surface of the abdomen. Another species, Phidippus formosus has been reported to bite, but the small amount of venom secreted causes only mild irritation, e.g., localized swelling and sensitivity. They are beneficial because they hunt and pounce on flies and other insect pests and eat them. They like sunny areas and are often found on porches or on walls.
Wolf spiders are robust and agile hunting spiders with excellent eyesight. They occasionally enter homes and garages and can be found almost anywhere inside. They are anywhere from ½ inch to 2 inches in length, depending on the species and are hairy, grayish or brown, with various markings on the back. The females are often seen carrying around her egg sac and then her babies on her back. Wolf spiders are not dangerous at all but will bite like any spider if it is squeezed or mishandled.
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