Don’t Touch: Tropical Spiders

Don’t Touch: Tropical Spiders

Tara A. Spears

One of the biggest shocks for visitors from cold climates is the absolute proliferation of creepy spiders in warm latitudes. Not only do these arachnids get bigger than in most places, but there are so many of them! Many have toxins and venoms that are very harmful to animals and humans.

I became aware of these insidious creatures the second month that I moved to Mexico. I returned home one evening, flipped on the kitchen light to discover a hideous, hairy, gigantic spider smack in the middle of the room! This real spider was nine inches in diameter- nearly as big as my dog! I grabbed a shovel and pounded the creature to death. I decided that I needed to

educate myself about spiders. Due to the lack of freezing temperatures, insects thrive year round so you never can stop being vigilant.

The word tarantula applies to two very different kinds of spider: the large wolf spider which brazenly creeps in the open, and the monkey spider, which is an excellent climber. This type of spider is long-legged, long-living, with the entire body covered with short hairs. These fine hairs are barbed and contain a mild venom.

Tarantulas inhabit tropical to temperate regions in South America and Central America, Mexico, and the southwestern United States, Asia, Africa and the Middle East. Despite their scary appearance and reputation, none of these fearsome-looking creatures make the list of deadly spiders (spiders having a strong toxin) that are dangerous to humans, but it is regarded as aggressive. The black

monster in my house was as big as a dinner plate. Tarantulas are nocturnal predators, killing their prey by injecting venom through their fangs.

There are few substantiated reports of tarantula bites proving fatal to a human. Because other proteins may get included when a toxin is injected, some individuals may suffer severe symptoms due to allergy rather than poison. Tarantulas will not bite unless provoked. However, just the bites of tarantulas can be quite painful since the fangs are large and can pierce all the way through the skin of the victim. I had recovered from the tarantula surprise visit only to see TWO of the

following spiders this weekend:

Scorpions: This unique looking spider is easy to tell at a glance from all the other spiders because they have the last five segments of the body modified to form a highly flexible tail. The tail is armed at the end with a sting consisting of a pair of poison glands, and of a sharp spine behind the tip. Like spiders they have four pairs of walking legs; but the legs of the second pair form a couple of powerful pincers, and those of the first pair two much smaller flippers. They feed entirely upon insects, mainly beetles or other ground species, although the larger kinds of scorpions have been known to kill small lizards and mice.

The large pincers are studded with highly sensitive tactile hairs, and the moment the prey touches these, it is promptly seized by the pincers and stung to death, the scorpion’s tail being swiftly brought over his back and the sting thrust into the struggling prey. Paralysis rapidly follows, and, when dead, the insect is pulled to pieces by the small nippers and its soft tissues sucked into the scorpion’s mouth. Scorpions vary in size from about 2 cm to 20 cm; and the amount of poison instilled into a wound depends mainly on the size of the animal, though the poison of some of the smaller species is more virulent than in the larger species. On humans, the effect of the poison is rarely fatal.

However, unless molested, scorpions are perfectly harmless, and only make use of the sting for the purpose of killing prey. Pretty or not, its number is up if it is in my territory. Now for the insidious, attitude changing spider:

Brown Recluse. As the name implies, this spider is brown and rather shy. This small brown spider has a backwards violin shaped mark on the back of his head. This mark also led the spider to be known as the “fiddle-back spider”. The venom of the Recluse causes ulceration. The Brown Recluse’s bite does not tend to be painful at the time of the bite and some people will not even know they have been bitten. In the first few hours the bite will only appear small and red like a standard bug bite but within 24 hours will begin to swell and blister. If bitten in fatty tissue a deep lesion will occur that may not heal for I would be remiss to not include discussion of the well- known Black Widow spider. The Black Widow Spider is known as

the deadliest spider in North America. The female of the species is a very glossy black with an hourglass present on the thorax. The hourglass mark is usually red but can range from yellowish to orange in color. The male of the species is smaller than the female and is not dangerous. The black widow spider venom is a neurotoxin, affecting the nervous system. The bite of the Black Widow is not generally known to be painful at the time of the bite but the bite will swell and two small fang marks will be seen.

The symptoms of the black widow bite are painful. The symptoms of this particular spider bite include: localized pain in the back and abdomen, sever cramping of the stomach, nausea, labored breathing, tremors, profuse perspiration, high blood pressure, restlessness, and fever. Though most bites do not lead to serious long term side effects they have been known to lead to death. Members of the widow family are found worldwide, particularly in the tropics. The species of widow that are found in the warmer areas of the world, are small, dark spiders with often hourglass-shaped white, red, or orange spots on their abdomens.

Lastly, our seaside tropic area is home to one other toxic spider. The Brazilian Wandering Spider,

also known as the “Banana Spider”, can be found in the jungles of North and South America. It does not have a web like standard spiders and can be found wandering on the jungle floor, hence its name. Though the jungle is this spider’s natural habitat, it is also commonly found in people’s homes. This spider is a very aggressive spider and tends to be nervous. This spider is usually found hidden in the vegetation of banana trees and has been found stowed away in banana crates. The Brazilian Wandering spider is known to be the most deadly spider in the Americas. Its venom can be fatal to a mouse in a dose as small as 0.006mg! The Brazilian Wandering Spiders’ venom is also a neurotoxin and is very painful due to it release of serotonin. An interesting side effect of this spiders bite is that it is

known to cause priapism, an erection that can last longer than four hours. Now this is one hardcore spider.

What you can do to avoid or control spider invaders: The consistent presence of spiders in structures is often a sign of insect infestation (think ants) as the spiders could not survive long periods without food. If this is the case, control efforts directed at the insects should eventually decrease or eliminate the spiders as well.

Removing spider webs and egg sacs along with frequent cleaning of closets, attics, and other storage areas will discourage the establishment of spiders.

Insecticides applied directly to spiders, webs, and areas frequented by spiders should control existing infestations. Insecticides available for spider control in and around structures include chlorpyrifos, diazinon, malathion, propoxur, pyrethrins, and resmethrin. These insecticides are registered under various brand names and in different formulations. Reinvasion from outdoors or the hatching of hidden eggs will make additional treatments necessary.

Although there are thousands of species of spiders in our area, only the ones listed in this article are harmful to humans. Just to be safe, don’t touch!