Venomous spiders - poisonous spiders
Venomous Spiders (poisonous spiders) may not be as big of a threat as many people believe. Antivenin against spider bite has become very effective and it is rare people actually die from a spider bite. In the United States an average of 6.6 people die from venomous spider bites each year1.
Spiders use venom to kill their prey after they have captured it in their web or captured by other means. A spider is only poisonous if one gets ill after eating it, so the term poisonous spiders is misleading and the correct word to use to describe these spiders is venomous.
Human injuries and fatalities
The probability of dying or getting seriously injured from a bite is very small - especially in the US. This is not an assurance of nothing will happen to you if bitten by a spider. If the accident happens, you should seek treatment.
Most spiders have evolved to capture small invertebrates and so spider venom is almost always harmless to humans. However, there spiders are exceptions to this rule:
Brown recluse spiders
The brown recluse spider is a misunderstood spider. It is indeed a very venomous and dangerous spider to people, but it is definitely not an aggressive spider and it only bites when threatened. Brown recluse spiders are also known as Loxosceles reclusa. Their bite can be quite bad. In South America recluse spiders are also know as brown spiders. In the US, a brown spider can be many different species; poisonous and non-venomous.
The Black Widows "~ Latrodectus. abc"
The genus Latrodectus includes the widely known black widows, notorious because of the extreme potency of their neurotoxic venom.
The genus comprises thirty-two recognized species and its occurrence is attributed to human mediated movement. It is found worldwide including places like Africa, the Middle East, Iberian Peninsula, Australia, New Zealand, North and South America, and Hawaii.
The recognition of taxa within Latrodectus has been considered problematic for a long time due to the difficulty associated with morphological features exhibiting geographic variation.
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Hobo spiders
Although hobo spiders are mainly found in the northwestern part of the US (Washington, Oregon, Idaho, Montana, Nevada) it seems like they are spreading towards other parts of the US such as California. California is not only hit by brown recluse spiders that have spread from Texas and Arizona, they are now also invaded by hobo spiders from north.
The Brown Widow Spider - coming to a place near you
Brown widow spiders are becoming more and more abundant in the US. Due to warmer weathers they are increasing in numbers. Brown widows are venomous/poisonous, and a serious concern to people in the US - although only few fatalities has been reported.
Camel spiders - not a true spider
Camel spiders are actually not spiders but something called solfugids, which is something in between a scorpion and a spider. They are also not venomous. However, as camel spider are quite interesting they are described on these pages also.
The jumping spiders "~ Phidippus. abc"
The Phidippus spiders are known as jumping spiders. They have a good sight which they use when capturing prey or finding mates.
Tarantulas "Poecilotheria. abc"
Children in some parts of South America keep tarantulas as pets. The South American tarantula is the world's largest spider and sometimes reaches more than 20 cm in length.
Tarantulas can be large enough to eat birds and a myth is that they even attack chickens from time to time.
Tarantulas in North America are significant smaller than tarantulas in South America. The one in the video is not endemic of the USA.
The tarantula has a bad reputation, but it is not really as bad as it looks. A bite from a tarantula can be painful, but it definitely won't kill you.
Wolf spiders
Wolf spiders are extremely common throughout the US. Females carry their egg sacs with them which is a special feature of wolf spiders. Wolf spiders are often found in peoples homes. Like all other spiders, wolf spiders try to find warmer places during the autumn, and most houses are warm and dry.
Others Venomous (poisonous) spiders "~ X. abc"
Explanations are found in the text. Species belonging to other groups of spiders can be very venomous as well. These spiders are also described in this webpage. From time to time more venomous spiders will be included in the list. If you want a spider included please don't hesitate to contact me. Comments, suggestions, pictures and relevant links are also very welcome.
References
1Langley, R.L. Animal-Related Fatalities in the United States - An Update Wilderness and Environmental Medicine Vol. 16 pp. 67-74 (2005)
Web links:
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Steve's pictures
Spiders of Australia
Arachnology
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