Facts and myths about spiders
The lands of the Imperial Valley are truly one of extremes, and offer a daily challenge for those who look to call it home. For those who brave its wilds for recreation, it is often a matter of survival.
This is especially true for those in uniform, who come to the Imperial Valley from around the world to train and understand what it means to exist in a desert landscape.
Summer 2018 saw Imperial Valley Desert Museum welcome and play host to visiting United Kingdom military personnel. Through a unique set of desert survival classes, these service members were introduced to the harsh realities of the western Sonoran desert. Relying on the history of early indigenous adaptation and survival, and modern understanding of the plants and animals of the region, IVDM staff taught how, if lost in the desert, to survive until help arrives.
Leading walks out into the desert behind the museum building, these visitors to our Valley experienced native animals first-hand, and they were most excited and cautious of the desert’s eight-legged residents. While the Imperial Valley has many varieties of spiders, it is the black widow, the desert recluse and the tarantula that capture the most attention. As the staff discussed these creatures with the military personnel, they dispelled myths and gave facts on these amazing creatures.
Black widow
The female black widow spider is considered the most venomous spider in North America, with venom 15 times as toxic as that of a rattlesnake.
Only the females are dangerous to humans: Males and juveniles are harmless. Widows seldom cause death, with only a 1 percent mortality rate, though you should seek medical care if bitten. Adult males will wander in search of females but do not bite. The myth that females kill and eat males after mating is only occasionally true, but usually the male escapes unharmed.
Widows are the best known and largest of the cobweb weavers. Widows spin webs that are erratic in appearance, and the silk is stronger than almost all other arachnids. The widow is nocturnal, and usually stays hidden in its web. Although not aggressive, widows will bite if the web is disturbed. After ensnaring its prey in the web, usually insects, the black widow makes small punctures in the victim’s body and sucks out the liquid contents.
desert recluse
Loxosceles deserta, or the desert recluse, is a small brown spider that is often confused with its infamous cousin, the brown recluse. There are 12 or 13 recluse spider species in the United States including the brown recluse, which is found in the Midwest, not California.
The desert recluse can be found in the open deserts of the Southwest, and is only found in cities near native vegetation. As the name “recluse” suggests, these spiders are shy. They retreat when possible, and prefer dark, undisturbed places near or on the ground for their webs, which are used for nesting, not for trapping prey. Desert recluse spiders usually live in large groups, so where one is found, there will be more.
The recluse is a nocturnal scavenger, preferring already-dead prey. Contact with humans usually occurs because they have taken temporary refuge in clothing or bedding. The bite of a desert recluse is generally non-fatal though, just like their Midwestern cousins, can lead to severe tissue damage and should be treated.
Tarantula
There are about 850 species of tarantula worldwide, and there are more than four dozen species in the United States. Typically, in the Southwestern United States, tarantulas live in solitude in desert basins, mountain foothills and forested slopes. Tarantulas in the desert live in burrows, and at the entrance they place webbing, which vibrates to send signals to the spider that potential prey is touching the strands. A tarantula will attack most creatures smaller than it: insects, other spiders, small lizards and mice. They don’t rely on the webbing to catch their prey, instead chasing after them and, once caught, injecting them with venom. Though they may be ferocious hunters, when they interact with animals larger than them, they are incredibly docile and even are kept as pets.
During mating season, which usually occurs in the fall, the males leave their burrows, sometimes to seek willing females. A male, encountering the silk surrounding the entrance to a female’s burrow, calls and dances to get the females attention. He may be rejected or embraced, but in either event, he may be eaten, to provide the female spider with energy to lay eggs. As tarantulas mature, they molt several times, each time shedding their old exoskeleton for a new one. The males may live for several years, the females, for several decades.
While these three spiders are only a small portion of the spiders we encounter all the time in our valley, they have gained notoriety worldwide. The staff at the Imperial Valley Desert Museum take great pride in discussing the creatures openly, honestly and factually. The members the U.K. military walked away from the museum with an appreciation and respect for these creatures with which we share our home.
The imperial Valley desert Museum is located in ocotillo. it is open Wednesdays through sundays, 10 a.m. 4 p.m.