The brown recluse spider is the most dangerous and deadly species of spider in the United States. While brown recluses (L. reclusa) are not native to Utah, the closely related desert recluses (L. deserta) are more commonly found in southern Utah, and reports exist of them venturing to northern parts of the state. These two species are extremely similar in appearance, and their bites are equally potent and dangerous. Being able to properly identify these spiders could be the difference between life and death, or it could at least save you from severe and permanent bodily harm.
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L. deserta and L. reclusa are so similar in appearance that differentiating them with the naked eye is nearly impossible. There are key attributes of both species that can be used to identify either, and any minuscule differences are ultimately immaterial since both species behave in the same manner and pose the same threat to humans.
- On average, ½ an inch in length
- Sandy tan to a darker brown color
- Desert recluses are typically slightly lighter in color
- Violin-shaped marking always on cephalothorax of brown recluse
- Occasionally also on desert recluse
- Abdomen with markings that sometimes appears grayish
- No markings on legs
- Relatively small pedipalps
- Unique eye placement
- Six eyes arranged in three sets
- Eyes are so close together that they appear as only three
- Two raised sets on the sides and one lower set in the middle
Recluse spiders account for the most common cases of false identification. The false sightings are due to a mixture of fear and a lack of knowledge about the appearance of a recluse. The easiest and safest ways to rule out a desert recluse or brown recluse are by identifying the size and the markings of a spider. If the spider you see is considerably larger than a U.S. quarter or if there are clear patterned markings on the legs or abdomen, you are most likely not dealing with a recluse spider.
Life Cycle And Behavior
As is the case with many spiders, male recluse spiders will attempt to impress the female in order to mate. The males perform a ritualistic dance that involves movements of his abdomen and pedipalps. If dancing fails, male recluse spiders will sometimes bring an offering of food to the female to persuade her. If his advances are accepted, the male deposits his sperm into a small web and uses his pedipalps to insert it into the female’s reproductive opening, similar to many other spiders.
Between May and July, the female produces several egg sacs that contain up to 50 eggs each.
Egg sacs are hidden in dark locations under nearby objects.
After hatching, recluse spiderlings venture off on their own very quickly.
Full maturity is reached slowly, between 10 and 12 months, and the spiders will molt 5 to 8 times before that.
Average lifespan for both species is between 1 and 2 years.
Recluse spiders are incredibly resilient creatures that can go several months or longer without any food. Aside from time spent finding a mate, recluse spiders stay very close to their nests throughout their lives. If desperate, recluse spiders will cannibalize one another, but their ability to abstain from eating makes this a rarity. Below are a few more unique facts about desert and brown recluses.
- They do not want to live near humans.
- They prefer natural environments with heavy coverage.
- Dimly lit, secluded areas are their ideal homes.
- Desert recluses prefer more arid environments.
- Recluses are nocturnal hunters, and they inject their venom into prey.
- They do not always inject venom when they bite.
- Smaller insects and bugs are the most common prey.
- Webbing is used for eggs and nests, not for hunting.
How Dangerous Are Brown Recluse Spiders?
The good news about dangerous recluse spiders is that they want nothing to do with you! While their venom can be extremely potent, reports of bites are relatively low due to their aversion to humans. If you do encounter one, it will almost certainly attempt to run and hide from you, and it will probably only attack you if it feels a physical touch.
Many people live near recluse spiders and never know it. The creatures tend to prefer outdoor environments, and they will have no need to enter your home if they find a suitable place to make their nests outside. If you do spot a recluse spider in your home, extreme caution must be taken, and professional assistance should be considered when it comes to extracting/exterminating them.
Recluses may not inject venom every time they bite, but effects of a venomous bite can quickly turn into a serious situation. The venom produced by these recluse spiders is capable of causing severe blistering, nausea, muscle pain, deep tissue necrosis, and even death. Though these effects are not the norm after a bite, the possibility of such severe and life-threatening symptoms justifies the fear of L. deserta and L. reclusa. If you believe you have been bitten by one of these spiders, you should immediately seek medical help before symptoms develop.
That you for reading our article on brown recluse spiders. Out last blog will teach you everything you need to know on another common spider in Utah, the yellow sac spider, and to learn about the 10 common weed types in Utah check out our most recent blog post!