Brown widow
| Brown widow | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Brown widow, female |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Latrodectus geometricus | ||||||||||||
| CL Koch , 1841 |
The brown widow ( Latrodectus geometricus ) is a spider from the family of the canopy-web spiders (Theridiidae). It belongs to the genus of the real widows ( Latrodectus ).
description
The females of the brown widow have a body length without legs of about 12 to 16 millimeters, the males are significantly smaller with 6 to 8 millimeters, but have longer legs. Phenotypically it has a wide range of colors. A brown widow can have any color from almost white to almost black, but a light brown color is typical. The color is not only individually different, but also changes in individual individuals in the course of their lives. Almost black forms can hardly be distinguished from the black widow. On the underside of the body she has an orange-colored drawing in the shape of an hourglass, which is typical for many Latrodectus species. The back is often dotted white, although color variations are also possible here.
The brown widow can best be identified by the cocoon she spins around her eggs. The cocoon is made of silk and is spherical in shape, with the silk forming spikes on the outside. The brown widow is described as very cautious, very few bites on humans are known, even if, as in Florida , it is quite common and does not shy away from being close to humans.
distribution
The brown widow is represented worldwide in southern latitudes. It probably originally came from South Africa, but it was introduced to all continents (with the exception of Antarctica ).
The spider has been at home in the USA for a long time, but has spread rapidly in the southeastern states since the mid-1990s, starting from Florida. Individual finds have also been reported from Arizona , Colorado and New Mexico . In southern California, their distribution now extends from Los Angeles County to San Diego County and east to Riverside County . The brown widow was first registered in Hawaii in 1939 and has since spread to all major islands.
In Japan there was the first reliable report on the occurrence of the brown widow in 1995 from the port city of Yokohama . By September 2008, it had spread to 11 Japanese prefectures. In 2004 a specimen was found near Pune , India.
The spider spreads between the continents by container ships. Their rapid spread within a country is due to the transport of goods with trucks. It is favored by the mild winters of the past decades, also in northern latitudes.
Way of life
The females live 3 years, the males only live 8 months or a year. The females mainly eat insects , but it has also been observed that small toads that got caught in their nets were also eaten.
The species is found in populated areas around houses, gardens, cars and mobile homes. It also colonizes plastic garden furniture, flower pots or leaves of bird of paradise flowers . As a rule, you can find them wherever there is a sheltered place.
Medical importance
The males are harmless, only the females bite, their venom is classified as less dangerous than that of the southern black widow ( Latrodectus mactans ) or the European black widow ( Latrodectus tredecimguttatus ), but it is also one of the most effective arachnids . As a rule, these spiders adopt a defensive stance in which they put their limbs tightly in danger. Only if they continue to be irritated can they become aggressive and bite.
Individual evidence
- ↑ a b Brown Widow Spiders IFAS Extension of the University of Florida
- ↑ a b Latrodectus geometricus . Brown Widow, brown button spider, geometric button spider Field Guide from the San Diego Natural History Museum
- ↑ Gordon M. Nishida and Joann M. Tenorio: What Bit Me? Identifying Hawai'i's Stinging and Biting Insects and Their Kin. University of Hawaii Press, 1993, pp. 12-13 ISBN 0-82481-492-4
- ^ H. Ono: Records of Latrodectus geometricus (Araneae: Theridiidae) from Japan . Acta Arachnologica, 44, 2, pp. 167–170, 1995 doi: 10.2476 / asjaa.44.167 (full text PDF, English)
- ↑ Shantanu Shukla, Vivek Gour Broome: First report of the brown widow spider, Latrodectus geometricus CL Koch (Araneae: Theridiidae) from India. Current Science, Vol. 93, No. 6, September 25, 2007, pp. 775-777. ( Online ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. )
literature
- Carl Ludwig Koch : The arachnids . Eighth volume, p. 117, Nuremberg 1841 (first description)
Web links
Brown widow in the World Spider Catalog
- Datasheet at Bugguide (English)
- Portrait of the University of Florida (English)
- Venomous Spiders in Florida (English)
- Photo Collection (English)