The Black Widow

While black widow spiders are the most venomous spiders in North America and the female of the species does represent some danger to humans, including death in certain cases, these cannibalistic creatures are far more dangerous to one another.
The black widow’s scientific name is latrodectus hesperus and is of the theridiidae family, the order aranaeae, sub order labidognatha, the arachnida class and the chelicerata sub phylum and arthropoda phylum and the genus latrodectus.
There are six species of black widows. The black widows in California spin webs that lack the shape, form and symmetry of the webs of many other spiders, but the rough and sticky silk of the webs is one of the strongest produced by arachnids. The web is produced by the females, which are much larger than the males. The spiders are nocturnal and typically hang upside down near the center of their webs and await insects to blunder into the web and get stuck. Prey caught in the web include a variety of insects and other arthropods. Once some prey has been snared in the web, the black widow punctures holes in the victim’s body and sucks out the moisture and contents, leaving a dried out shell.
Webs are found in dark and recessed places, such as the base of trees covered by leaves, the underside of logs, rocks, ledges, around plants and debris, and undisturbed areas wherever a web can be strung. Cold weather, hot weather, rain or drought may drive these spiders into buildings. Garages are a popular residence for latrodectus hesperus.
Females are distinguished by their jet black coloration on all of their bodies with the exception of a red hourglass on their abdomens.
A female black widow spider weighs less than a gram and can grow to about an inch in length, reaching one-and-a-half inches with legs extended. They reach sexual maturity in seventy to ninety days. Males are about half the female’s size, with smaller bodies but longer legs.
Male black widows frequently have yellow and red bands and spots over their backs, as do both genders of black widows in their immature stages.
They mate in the spring. Incubation takes roughly fourteen to thirty days. A female will deposit 250 to 700 batches of eggs in a single sac, a white-to-tan egg case of about a half inch diameter, which is suspended within the web. One female will produce four to nine sacs per year. Of the 250 to 700 eggs inside the sac, usually it is only the ones that hatch first that survive since, once they come to life, they begin eating the eggs surrounding them. Thus, as few as one but usually somewhere in the neighborhood of a dozen young spiders will emerge from the sac. The spiders live typically 18 months but have an upward longevity of three years.
This cannibalism persists into adulthood, as females sometimes, though not always, eat their mate. This hostility toward their husbands is rooted less in hunger as on an instinctive reaction to prevent the males from themselves feasting upon the offspring in the sacs laid by the females.
Newly hatched spiderlings are predominately white or yellowish-white, gradually becoming darker and then entirely black, with varying amounts of red and white with each molt.
Females molt six to eight times and males three to six times. Females mature about 90 days after egg sac emergence and live another six months to a year or more. Males mature about 70 days after emergence and live only another month or two.
Adult male black widows appear to be aware of their spouses’ aggressive nature and appetites, but seek out females for the purposes of spawning, nonetheless. Upon mating, the males grow less wary and, indeed, careless.
A male will court its mate by tapping the female’s web with its front tarsi, rhythmically jiggling the silk with his pedipalps, its body jerking spasmodically and its abdomen vibrating at a high frequency. Females frequently initially reject this display and may charge the male, in which case the male retreats. If the female does not charge or if she ceases to charge, the male will approach the female cautiously and cut the web at strategic points to effectively reduce the female’s potential routes of escape. The male will at this point caress the female’s legs, then her abdomen, and ultimately climb excitedly over her body. A courting male will frequently “throw silk” about the female at this point, forming the so-called “bridal veil.” He then positions himself venter to venter with his mate. Successful males then locate the female epigynum and insert first one, then the other, palpal organ . The time consumed in this coupling can range from 10 minutes to 2 hours. Males that succeed in insemination often unsuspectingly linger in the vicinity of their mates or wander leisurely away, in marked contrast with the initial cautious approach and escape strategies characteristic of males prior to insemination. Scientific observers monitoring more than two dozen mating encounters actually witnessed just one male who had succeeded in inseminating a female being eaten by his mate immediately after mating. However, several were later found dead in their mates’ webs.
Though the female black widow’s venom is very powerful, roughly 15 times as potent as the venom of some rattlesnakes, black widows are not aggressive unless threatened and usually do not dispense enough venom to be fatal to humans, although they have killed toddlers and elderly people with their bites.
The black widow is prey to mud-dauber wasps.

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