Alright folks, I am finally resuming my “weekly widow” posts. Here we have Latrodectus Mactans, also called the Southern Black Widow. It is often considered the classic “Black Widow”. According to Bugguide.net, the name Latrodectus Mactans is a mixture of both Latin and Greek and is translated as “murderous biting robber." Though Southern Black Widows are not aggressive, the venom of the female is a neurotoxin. Females (see photo) are glossy black with a red hourglass shape on the underside of their abdomen, they often also have a spot of orange or red near their spinnerets. Males of this species often look less like the females and more like juveniles which are usually lighter in color and have white-ish stripes on the sides of the abdomen with spots running down the center of the abdomen which can range in color from yellow to red. Males are harmless. Latrodectus Mactans are found mainly in the Southeastern United States.
Latrodectus mactans - Southern Black Widow - Female - 12mm
Found beside my storage building. Very common here.
I have never seen one exhibit any aggressive behavior. Last year within 50 yards of my home I collected over 60 males and females, and relocated them.
Information from BugGuide.
It ranges as far north as southern New York, as far south as Florida, and as far west as Texas, Oklahoma, and Kansas. (L. mactans has been found in California, possibly indicating that it can be found in any southern state.) The Southern black widow spider also occurs throughout all four deserts of the American southwest.
In addition, Latrodectus mactans has been found in parts of southern Canada.
Mating takes place in spring or summer. Black widow spiders reproduce sexually where the male inserts his palpus into the female’s spermathecal openings. The notion that female always eat the male after mating is incorrect! Females have been observed killing and eating the male after mating; however, a large majority of males do escape, especially when he doesn’t remain around the web after mating, and the female is already well-fed.
The female lays eggs onto a web where they are camouflaged and guarded. A female black widow spider can produce nine egg sacs in one summer, each containing about 400 eggs . Usually, eggs incubate for 20-30 days, but more than 12 rarely survive through this process, due to cannibalism. It takes two to four months for black widow spiders to mature. The female live on for 180 days after maturing, while a male only lives on for another 90 days. In addition, the female Latrodectus mactans can store a lifetime supply of sperm to fertilize all the eggs she will ever produce.
Caution: This spider is venomous and can harm people. However, the female injects such a small dose of venom that it rarely causes death. Reports indicate human mortality at well less than 1% from black widow spider bites.
While Latrodectus mactans is not aggressive and does not have the instinct to bite, her venom is neurotoxic, which means that it affects the transmission of nervous impulses. Black widow venom acts by causing a localized release of the neurotransmitter acetylcholine, which is involved in muscular contraction. A bite results in a severe, uncontrollable, and prolonged muscle contraction in the area of the bite.
If the black widow spider bites, most likely it has been pressed against human bare skin, and this causes a natural reaction, a bite in self-defense. For the most part, the black widow’s bite may be felt only as a pin prick, during which the spider’s fangs inject a minute amount of highly toxic venom under the skin. The severity of the victim’s reaction depends on his or her age and health, and on the area of the body that is bitten. Local swelling and redness at the site may be followed in one to three hours by intense spasmodic pain, which can travel throughout the affected limbs and body, settling in the abdomen and back (intense abdominal cramping, described as similar to appendicitis), and can last 48 hours or longer. Elderly patients or young children run a higher risk of severe reactions, but it is rare for bites to result in death; only sixty-three having been reported in the United States between 1950 and 1959 (Miller, 1992). Other symptoms can include nausea and profuse perspiration. If left untreated, tremors, convulsions and unconsciousness may result. When death does occur, it is due to suffocation.
The Black Widow is considered the most venomous spider in North America, and it is reported that the venom of Latrodectus mactans is 15 times more toxic than a rattlesnake’s.