Black Widow Spider (Latrodectus mactans)

              

Class:	Arachnida
Order:	Araneae
Family:	Theridiidae
Size:	Length: 1 to 1.5 inches (2.5 to 4 cm)
Weight:	Unknown
Diet:	Flies, moths, ants, beetles, and other spiders
Distribution:	North and South America, Africa, Australia, Southern Eurasia
Young:	250 to 900 or more eggs
Animal Predators:	Mud-dauber wasps
IUCN Status:	No special status
Terms:	Young: Spiderling
Lifespan:	Females: 5 months to 1.5 years   Males: 2 to 4 months.

 

Facts/Trivia:

·         Because they inject only a small amount of venom, black widows are not often deadly, but a bite will cause severe pain and discomfort. 

·         Black widow venom is 15 times more potent than rattlesnake venom.

·         In over 200 years, 55 people died in the U.S. from black widow bites.

·         Young, growing spiders are capable of growing back missing legs.

 

Description

Females are much larger than the males and are shiny black, usually with a red hourglass shape on their back. The male is half the size of the female, with longer legs and he often has light coloured stripes on his abdomen.

 

Habitat

Black widow spiders usually live in the warmer regions of the world, including the United States, Asia, Africa and South America, but they can also be found on the southern prairies of Canada. They build their nests outside on the underside of rocks, plants, woodpiles, outhouses, ledges or other places where they will not be disturbed.

 

Feeding Habits

Black widow spiders hang belly upward and rarely leave their web. Black widows ensnare their prey in their web, then make small punctures in the body and suck out the liquid contents.

 

Reproduction

Black widow spiders mate in spring and contrary to the popular belief that females always eat males after mating, it is only after several matings, when the male becomes weak, that the female eats him. This is why they are called black widows. The egg sac is suspended in the web and holds 250 to 900 or more eggs, which will incubate for 14 to 25 days. The brown oval egg sac has a paper-like texture and is only about ½ inch (1.27 cm) long. The spiderlings are either white or creamy-white in colour, but gradually turn to black as they moult. Both male and female spiderlings are harmless. 

 

Behaviour

Black widow spiders build webs that appear tangled and without form, but the black widow’s silk is stronger than almost all other arachnids and they know immediately when prey has been caught in it. They rarely leave their webs and are non-aggressive to humans unless threatened. 

 

Conservation 

The black widow spider is not a conservation concern.

 

Sources

http://www.desertusa.com/july97/du_bwindow.html

http://www.ext.vt.edu/departments/entomology/factsheets/blackwid.html

http://homepage.powerup.com.au/~glen/widow.htm

http://ipmwww.ncsu.edu:8150/AG369/notes/black_widow_spider.html

http://animaldiversity.ummz.umich.edu/accounts/latrodectus/l._mactans$narrative.html

http://www.aqua.org/animals/species/venom/bwidow.html

http://personalwebs.myriad.net/bugboy/blackwid.htm

Black Widow Spider Wildlife Fact File, IM Pub, US