Florida Spiders: More Friend than Foe?

Last December I was visiting a local ranch to consult with the owner on their pasture health. The entire time I was walking the field I felt annoyed by a bit of something in the toe of my boot. Now, as a Florida girl, I know the importance of shaking out ones boots before putting them on, but I figured a bit of hay must have slipped in and wadded itself up at the toe. Not wanting to de-shoe in front of a client I dealt with it until I was back in my truck, at which time I promptly took my shoe off and gave it a good shake. Imagine my absolute horror when what fell out was not a wad of hay but a full sized Wolf Spider! I nearly fainted!

As the UF/IFAS Lake County Livestock Agent I have a deep and abiding appreciation for all animals. Well, all animals except spiders. I detest, loathe, hate, and if I am honest, am more than a little phobic of spiders.

After my on-farm close encounter of the arachnid kind, I called a good friend, who happens to be an ecologist, looking for a little sympathy. I was hoping that he would affirm my assertion that all spiders should be eradicated from the face of the earth… but I was instead met with some cold, hard, science-based facts about why spiders are absolutely vital to a healthy ecosystem and to agriculture.

Not only do spiders keep insect populations in check (you think our mosquito populations are out of control now? Without spiders they would be a hundred times worse), they also serve as part of a balanced diet for other, larger, less terrifying wildlife like birds and bats. Spiders play a major role in managing agricultural pests as well. Without spiders farmers would lose far more crops to pests and rely more heavily on pesticides.

Additionally, spiders lend a helping hand (or eight) to human engineers who study their web design for clues on making man built structures more stable. Spider silk has a higher strength-to-density ratio than steel and may have future applications in the manufacture of bulletproof material. Scientists have also used spider venom to develop new treatments and medications.

Turns out my spider eradication plan had some serious shortcomings.

The most common spiders in Florida include Jumping Spiders, easily identified by their three rowed eye arrangement. These feisty little fellows don’t bother spinning webs and instead actively hunt their pray, pouncing on their victims instead of ensnaring them. Crab Spiders, another common Florida arachnid, hold their legs out to the side similar to the way a crab does. Like their jumping cousins, Crab Spiders forgo web building and rely on ambush tactics instead.

The Golden Orb Weaver makes up in web design what the Crab and Jumping Spiders lack. These large colorful arachnids, also known as Banana Spiders, spin enormous webs that can span over three feet in length. They are commonly found in the woods and will place their webs in clearings or along trails to catch flying insects. If we ever go on a trail ride together and I insist you ride in front, you now know why. Wolf Spiders, another common Florida spider, are ground dwellers and like to hide in dark places (like, say, a boot). These large spiders have excellent eyesight and are sensitive to vibrations.

There are five species of venomous spiders in Florida: the Southern Black Widow, the Northern Black Widow, the Red Widow, the Brown Widow, and the Brown Recluse. In our area the Southern Black Widow is the most common venomous spider. They have a glossy black appearance with a distinct hourglass marking on the underside of the abdomen. Black Widows prefer to hide outdoors and favor dark places such as the undersides of rocks, woodpiles, and boards. A bite from one of these spiders feels like a pin prick initially. This minor pain is rapidly replaced muscular cramps, typically in the shoulder, thigh, and back. If left untreated, blood pressure will rise and the victim may experience nausea, sweating, and difficulty breathing.

The Brown Recluse is not native to Florida, nor has a breeding population been established. Brown Recluses do occasionally hitch-hike into Florida on out of state shipments. They are recognizable by a distinctive violin shaped marking on the head and thorax. Those unlucky enough to be bitten by a Brown Recluse will typically not feel pain initially. A blister develops at the site of the bite, the area becomes inflamed, and the tissue will die away leaving a sunken sore. Recovery from a Brown Recluse bite may take as long as two months and often results in permanent scarring.

The chance of finding or being bitten by a Brown Recluse in Florida is extremely slim, yet hundreds of bites are reported every year. Some entomologists have theorized that the Brown Recluse may be being blamed for necrotic infections that are actually caused by ticks, viruses, bacteria, or fungi.

If you are bitten by a spider it is a good practice to preserve the offender in rubbing alcohol for identification. The majority of spider bites are not dangerous, but if you suspect that you were bitten by a Widow or Recluse it is important to seek immediate medical attention. If you find a spider in your house you may choose to coexist peacefully with him or gently relocate him outdoors. Oh, and always, ALWAYS shake out your boots with vigor!


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Posted: November 3, 2020

Category: Natural Resources, Wildlife
Tags: Insects, Spiders, Wildlife

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