Most Dangerous Spiders in California
There are two types of spider that are capable of delivering venomous bites of note in California, qualifying them as being the most dangerous: widows and recluses.
Although threatening to humans, death from a widow bite is rare nowadays thanks to the development of anti-venom. Pain and discomfort is most likely to be the worst result of a bite, and often there may be little or no effects.
Recluse bites tend to be rarer than widow ones in the state, thanks to the desert recluse not generally living in close proximity to humans and Chilean recluses only being present in a few limited areas of the south. The most common species of recluse spider found in the USA, the brown recluse, does not inhabit California.
Widows and recluses can potentially be found both indoors and outdoors. You can lower the chances of getting bitten by one of these spiders by:
- Being able to clearly identify each type of spider
- Having an understanding of the sorts of places where you are likely to encounter them
- Taking sensible precautions, such as wearing gloves when reaching into places where you cannot see, such as high shelves and dark corners, particularly in sheds and outhouses.
- It is also advisable to shake out old clothes, towels, linen, etc. that hasn’t been used for a period of time, before you put them on to wear.
Below is a full description of each spider type, including their common habitats, behaviors, and venomous bites.
Widow Spiders in California
As its name suggests, the Western Black Widow (Latrodectus Hesperus) is found across western regions of the USA.
The females are the ones to look out for when it comes to venomous bites. They are jet black in color and have the distinctive red hourglass markings on their lower abdomen (although in some cases, the hour glass can be yellow in color, or even occasionally white).
The males are brown to orange in color and generally pretty harmless. The female eating of the male after mating is actually rare in this species and the male often gets to mate numerous times.
Widows are nocturnal and build messy looking, three-dimensional webs. They will commonly hang upside down near the center and when they sense an insect getting caught (usually through vibration, rather than by vision), they run over and bite the insect, before covering it in their silk.
Widows have a fearsome reputation when it comes to venomous bites, but the truth is that you are unlikely to die when bitten unless you are particularly old and frail, or a young child. Treatment should always be sought straightaway, however.
It should also be noted that Widows are generally timid and will almost always try to run away if they feel threatened. The only exceptions to this are when a female spider is guarding her eggs, or when a Widow is accidentally pinched or pressed against - this can occur when someone puts on old clothing such as a glove or shoe and there is a spider inside it, or if someone is reaching or feeling around in an area where a widow is dwelling, such as a high shelf or dark recess.
Note that the bite itself may feel like just a small pin prick at the time, or may not even be noticed. Symptoms don’t usually start until 1 to 3 hours after the poisonous bite and may include:
- Severe pain
- Muscle and abdominal cramps
- Convulsions and tremors
- Excessive sweating
- Lesions in the bite area
To start with, the venom just affects the area of the bite, but then it gradually it travels around the body via the lymphatic system, before getting into the bloodstream. Symptoms normally persist for 3 – 5 days maximum. It is extremely unlikely that a Widow bite will be fatal if the victim receives medical treatment.
Recluse Spiders in California
The desert recluse is the commonest type of recluse to be found in California. This species inhabits the eastern desert regions of the state. Bites from these spiders are rare as they are not usually found in high population areas, so encounters with humans are limited.
There are also Chilean recluses in the Los Angeles area of California. These are considered one of the more toxic species of the recluse family.
(Although brown recluses are common in many other parts of the U.S., they don't live in California.)
As their names suggests, recluse spiders are not aggressive by nature. They tend to bite only when pressed against human skin, for example when an article of clothing is put on which a recluse is living in.
Recluse spiders are generally timid and seldom seen by humans. Bites usually occur when someone reaches or feels around in an area that they can’t see, or when someone puts on an old item of clothing that the spider was hiding in.
The effects of a recluse bite can vary enormously, from virtually no effect, all the way up to death (in very rare instances).
Symptoms of a bite typically start between 2 and 6 hours afterwards and can include:
- Severe pain
- Necrosis at the site of the bite
Unfortunately, there is no effective antivenom for recluse bites, but medical care should still be found as swiftly as possible.
It should also be noted that most recluse bites are unremarkable.
You can best avoid a recluse bite by:
- Not leaving clothes, gloves, shoes lying around on the floor, if possible, and shaking them out before you put them on.
- Not reaching into areas where you can’t see, especially shelves and recesses in sheds and outhouses.
- Recluses are not naturally aggressive but will react aggressively if they feel that their life is threatened, or they are trapped.
- "Black Widow Spiders". Orkin Pest Control. Retrieved 19 June 2017.
- Burkhard Bilger (March 5, 2007). "Spider Woman: Hunting venomous species in the basements of Los Angeles". The New Yorker.
- Vetter, Rick. "Myth of the Brown Recluse Fact, Fear, and Loathing". UCR Spiders Site.
- "Western Black Widow (Latrodectus hesperus)". The Royal Alberta Museum. The Royal Alberta Museum.
© 2013 Paul Goodman