Black widow spider
The black widow is a glossy black spider with a round abdomen when it's a female and a more oval shaped abdomen when it's a male. The common name for this spider is «the black widow». The name black widow is given because of the habit of females to eat their male after mating.
This habit has been observed in closed containers. It is likely, that the observations of large females eating smaller males is more due to the fact that there were no places for the males to escape.
The abdomen of the black widow is black but can take other colors as well.
The black widow and certainly the mactans is the largest spider in the family Theridiidae. The female is 8-10 mm long and is identified by two distinctive red hourglass formed spots on its abdomen. Latrodectus mactans is found in USA and the West Indies.
Another well-known black widow is the red back spider. More about the red-back is found further down on this page.
Ballooning
Young spiders of the genus, including young Latrodectus mactans are often dispersed by the wind, a phenomenon known as ballooning. The small and light spiders climb to the top of a tree or something else, and allow an air current to carry them to somewhere else.
During mating, the male spins «sperm-web» and deposits semen on it. His palps are then charged with the sperm. He then abandons his habitat, and locates a female.
The web of black widow spiders
The web of the black widow is an irregular tangled mass and contains a silken retreat where she can hide. The female hangs upside down in her web where she defends her egg sac. Most bite to humans occurs as a part of defense against attacks on a web.
The male is about half the size of the female and has a more oval-shaped abdomen. The male's legs are longer and it has a spotted appearance.
The female black widow is very venomous, but the males aren't. The poison glands of a male aren't functional in its adult stage.
Life Cycle
Courtship begins when the female black widow spider has been located. During copulation the male inserts his papal organs into the spermathecal openings of the female and the spermatozoa are released onto the eggs. Research suggest, that once a female Latrodectus mactans has mated, she can store a lifetime supply of sperm to fertilize all the eggs she will ever produce.
Habitat
Black widow spiders are commonly found outdoors and around human habitation. It has been found in containers, in rubbish and on or under the seats of outdoor toilets where it thinks it can stay undisturbed. Other places where this spider is often encountered beneath logs, bark, sides of rocks, etc; always close to its web.
Black Widow Spider Bites
A bite from a black widow can cause severe abdominal muscle spasm. A bite from a black widow can be distinguished from other insect bites by its two puncture marks in the skin. Antivenin is available so collect the spider to the doctor if possible and let the doctor see her.
Red Back Spider
It's called the Red Back Spider due to the markings on its abdomen. Its Latin name is Latrodectus hasseltii. The body of a female red back spider is around 0.4 inches and the size of a male is around 1.2 inches. The female produces up to twelve yellow egg sacs, each with approximately 250 eggs in it.
The female red back spider has a black body with white markings on the upper side of its abdomen. It also has the characteristic red hour-glass marking on underside of abdomen. The abdomen of the red back spider is shaped like a pea. Both male and female has long slender legs.
Bites from red back spiders
A bite from a hasseltii is highly venomous and characterized by intense pain and around the bite site.
The symptoms from a bite may include sweating, muscular weakness, nausea and vomiting. It usually starts with a sharp pain, then the bite site becomes hot and an oedema develops rapidly. Swelling is limited to an area of up to five cm in radius from the bite site. Five minutes after the bite the pain commences and increases in severity and distribution. About thirty minutes after the bite swelling are experienced in lymph nodes near the area of the bite. Other symptoms have occurred as well. One must be extremely careful handling these animals.
Life Cycle
The female black widow can store sperm and use it up to two years after mating to lay eggs. Each egg sac contains more than 200 eggs and she can lay several egg sacs in one season. The sacs are distributed in her web. «Baby spider» spreads by the wind. The female often eats the male following mating. A link to a video showing the mating can be found in the navigation panel. Females may live for two to three years and males only for three or four months.
Black widow (the red katipo) - New Zealand black widow
Latrodectus katipo is one of two widow spiders in New Zealand. L. katipo is endemic of New Zealand but unfortunately it is threatened with extinction for a number of reasons. L. katipo is also called the red katipo while the black katipo actually is a L. atritus.
The red katipo is endangered because its habitats are being destroyed by forestry. This is especially the case in Northern parts of New Zealand.
Appearance
The black katipo spider, L. atritus, is characterized by the absence of the characteristic red stripe on its abdomen. L. katipo has the typical red marks. The red black widow has a size of approximately 25 mm. Also this cobweb spider is also characterized by its untidy web. The size of the male is approximately 1/6 of the females size and the male resembles juvenile female black katipo's.
Habitat of the red katipo
The red katipo black widow likes to stay in certain types of grass and sand and or under logs, stones or under woods. In a larger survey from New Zealand a lot of specimens were also found in sand-dunes.
Bite
A bite from the red black widow can be fatal and deaths have occurred in both New Zealand and Australia.
The venom causes pain that develops and spreads within a few minutes. The pain is accompanied by sweating, difficulty in breathing and vomiting. The degree of effect from a bite is proportional to the amount of poison injected into the bite wound.
Miscellaneous
The black katipo is a kind of national invertebrate symbol in NZ. It appears on websites, t-shirts in e-mails, so it can be considered quite popular. This might be due to its status as a symbol of invertebrate conservation.
Other black widow resources in the internet
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