Black Widow Spiders

Adult black widow spiders have a shiny, black, rounded, circular abdomen and
are about 1/3 inch long (about 1-1/2 inches when their legs are spread).
Adult spiders have two reddish or yellowish triangles on their bottom which
looks like an hourglass marking, and their body color is dark colored usually
black or sometimes dark brown. They are usually recognized because of their
red or red-orange hourglass design on the bottom of their abdomen. This
pattern is changeable and may look like two separated spots. In some spiders
there is no pattern on the abdomen. The immature stages of both sexes of the
widow spiders have red or red-orange or yellow spots and strips on the top
of their abdomen. Females are colored gray or pale brown. Their color gets
darker as they get older. The hourglass pattern on the underside of the
abdomen forms throughout their development. Male widow spiders are smaller
about 1/4 inch long, and they\'re usually not black in overall color, instead
it looks like a light brown or gray. Male widows have an hourglass pattern
too. When they are full-grown they have large knob-like shapes called
pedipalps, which start from the head. But to females they still look the
same. Newly hatched spiderlings are white or a yellowish-white, eventually
turning blackish when they get older. Adolescents of both sexes look like
the male.
Black Widow spiders build loose and uneven mesh-type webs of rough silk in
dark places usually outdoors. And build their webs near the ground
(sometimes inside of houses) but mainly they build them outside. Black
Widows can be found near the ground in dark undisturbed areas. Nest sites
are near holes made by small animals, or around construction openings and
woodpiles. Also they can be found around low shrubs which are usual sites
for widow spiders. Black widows are also found inside in dark undisturbed
areas like behind furniture or under desks and in undisturbed basement areas
and crawl spaces of homes are areas where black widow nests are. They don\'t
produce a web like the weaving spiders do or the funnel pattern webs that the
funnel weaver spider\'s make.
The female lays eggs in silken cocoon sacs about 1/2-inch in width. The sack
is a pear shaped, and is a creamy yellow, light gray, or light brown in
color. They usually lay about 300 to 400 eggs per sac and have 4 to 9 egg
sacs made during a summer. But only 1 to 12 young survive after the egg
incubation period of about 14 to 30 days because of cannibalism. Growth
requires 2 to 4 months depending on availability of prey during which the
females shed 6 to 8 times and the males 3 to 6 times. Females mature 92 days
after the egg sac outburst and live for about 179 days, while males mature 71
days after outburst and live for 30 days. Because usually the female eats
the male after they mate. But sometimes if females are well fed, the males
get away to mate for another day. The females hang belly upward and very
rarely leave the web. In cold weather and droughts it can cause these
spiders to go into buildings. Prey caught in the web include a many
different insects (cockroaches, flys, and beetles) and other arthropods. The
female black widow is shy and usually only goes out at night. But when she
leaves her web she usually goes far away from her the web. Outbreaks of
black widows occur off and on. Some years an area may have thousands of
widows and the next year they may be gone. Certain kinds of habitats such as
sand dune areas may have black widows every year. Alternating warm and cold
weather during the winter and spring months are harmful to their survival.
The venom of the black widow spider is 15 times as toxic as the venom of the
prairie rattlesnake. However, only a small amount of the toxin is injected
with a single bite by the spider, while the relatively large amount of
injected rattlesnake venom results in about 15 to 25 percent mortality among
those bitten.
The severity of a person\'s reaction to the bite depends on where you were