Southern black widow

Appearance

The mature female is around 1.5 in long and 0.25 in in diameter. She is shiny and black in color, with a red marking in the shape of an hourglass on the ventral side of her very rounded abdomen. There is much variation in female size, particularly in egg-carrying females. The abdomen of a gravid female can be more than 0.5 in in diameter. Many female widows also have an orange or red patch just above the spinnerets on the top of the abdomen.

The male is either black, or closer to the appearance of the juveniles in color, and is much smaller with a body of less than 1/4 inch .

Juveniles have a distinctly different appearance to the adults, the abdomen is grayish to black with white stripes running across it and is spotted with yellow and orange.

Reproduction

When a male is mature, he spins a sperm web, deposits semen on it, and charges his palpi with the sperm. Black widow spiders reproduce sexually when the male inserts his palpus into the female's spermathecal openings. The female deposits her eggs in a globular silken container in which they remain camouflaged and guarded. A female black widow spider can produce four to nine egg sacs in one summer, each containing about 100-400 eggs. Usually, eggs incubate for twenty to thirty days. Rarely do more than a hundred survive through this process. On average, thirty will survive through the first molting, because of cannibalism, lack of food, or lack of proper shelter. It takes two to four months for black widow spiders to mature enough to breed, however full maturation typically takes six to nine months. The females can live for up to five years, while a male's lifespan is much shorter. The female, on occasion, eats the male after mating. Lifespans depend upon environment, with shelter being the greatest determining factor and food the second greatest. Males that escape being consumed by the females can go on to fertilize other females. It is a widely held misconception that females eat males after every mating.