![]() The combination of the dark black color, the irregular web shape, and the distinctive spherical abdomen are useful characteristics for separating widow spiders from other spider species. They do not produce the symmetrical web typical of orb weaving spiders (Araneidae) or the distinctive dense and funnel patterned web of the common funnelweb spiders (Agelenidae). Therefore, widow spiders are most often found in abandoned rodent burrows, loose stone or wood piles, or the corners of rooms, garages, and outbuildings. ![]() Widow spiders often live in ready-made holes in dark, undisturbed sites. Widow spiders build sticky irregular mesh-type webs, typical of other spiders in the cobweb spider family (Theridiidae). Aside from this last feature (conspicuous pedipalps) they are similar in appearance to immature females. When mature, they have large knob-like structures (pedipalps) originating from the cephalothorax, or first body segment. Male widows may have the characteristic hourglass pattern, but coloration is often more orange and sometimes yellow. (The body of the males typically range from 1/8 to 1/4-inch in length.) They are not usually black in overall color, instead appearing light brown or gray and banded. Males of the western widow are onehalf to one-third the size of females, and they have a more elongate body form. The presence of an “hourglass” pattern on the underside of the abdomen occurs throughout their development. Darker coloration increases as they get older. Immature females can be colored gray or pale brown, with banding patterns. The immature stages of both sexes and adult male widow spiders may have red or red-orange or yellow spots and stripes on the top of their abdomen. The color of the “hourglass” may fade or intensify in color during the life of any individual widow spider. The pattern may appear as two unconnected spots, as a roughly rectangular area, or be so faint as to be barely visible. However, this pattern can be highly variable with the western widow. ![]() The distinguishing feature of all widows ( Latrodectus spp.) is the presence of a red or red-orange “hourglass” pattern on the underside of the abdomen. Adult females are distinctively shiny and dark colored, generally black or occasionally dark-brown. They usually reach a length of 1/4 to 1/3 inch. Mature females of the western widow spider are generally round in form with a bulbous abdomen. (The “true” black widow, Latrodectus mactans, is more common in eastern and southern areas of the country.) Identification Figure 1. Several species occur in the United States, but the western widow, Latrodectus hesperus, is the overwhelmingly dominant species throughout Colorado. The “widow” spiders are a group of related spiders in the genus Latrodectus. Outdoor nest sites include holes produced by small animals or around construction openings and wood piles. Widow spiders prefer to nest near the ground, in dark, undisturbed areas.Muscle and chest pain or tightness are some of the most common reactions to the widow toxin. Widow spiders produce a toxin that affects the nervous system.Bites may be more likely if the female is tending an egg sac in the web, which she will defend. Widow spiders rarely, if ever, bite when not within a web.
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