Venomous Spiders: Species, Fatalities, Bites, Webs, and Natural History
Human Injuries and Fatalities
The probability of dying or getting seriously injured from a bite is very small—especially in the U.S. This is not an assurance that 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 are exceptions to this rule:
Brown Recluse Spiders
The brown recluse spider is not as bad as its reputation. It is indeed a very venomous and dangerous spider, 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 U.S., 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.
Although hobo spiders are mainly found in the northwestern part of the U.S. (Washington, Oregon, Idaho, Montana, Nevada), it seems like they are spreading towards other parts of the U.S., such as California. California has not only been hit by brown recluse spiders that have spread from Texas and Arizona; they are now also being invaded by hobo spiders from the north.
The Brown Widow Spider—Coming to a Place Near You
Brown widow spiders are becoming more and more abundant in the U.S. Due to warmer weather, they are increasing in numbers. Brown widows are venomous/poisonous and a serious concern to people in the U.S.—although only few fatalities have been reported.
Camel Spiders: Not True Spiders
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 spiders 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 good sight, which they use when capturing prey or finding mates.
Tarantulas: "Theraphosidae. spp"
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 significantly 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 are extremely common throughout the U.S. Females carry their egg sacs with them, which is a special feature of wolf spiders. Wolf spiders are often found in people’s 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.
1Langley, R.L. Animal-Related Fatalities in the United States - An Update Wilderness and Environmental Medicine Vol. 16 pp. 67-74 (2005)