Spiders – A Gardener’s Friend (mostly…)
May 19, 2011
Hello, Friends of Enota!
A week or so ago we wrote a series on garden pests. Today we will take an interesting look at a garden friend – the spider. (Yes, the spider!) Many of us have a love/hate relationship with spiders…
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We have no problem working outside and having bees buzzing around us. Honeybees especially, couldn’t care less that we are working around them, as long as we don’t make any overly aggressive moves toward them. Carpenter bees, bumblebees and most wasps don’t pay much attention to us either. A praying mantis crawling on a bare arm is no threat at all….
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But spiders seem to give us the creeps. Discovering a spider crawling on our clothing can make us dance! There are poisonous spiders, as we will note later in this post; and, perhaps that is why so many of us are “creeped out” by spiders….
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When we posted here before about beneficial insects in the garden, we barely mentioned spiders. But then, spiders are not insects. They are in another whole class by themselves. The class arachnida. (Ticks and mites are also in this class and we don’t much like them either, although they don’t seem quite as scary.) If it were not for the venom thing, gardeners could really love spiders! A knowledgeable gardener would not kill spiders outside the living quarters. That’s because spiders are so much more effective at killing the bad bugs that we don’t want in our gardens. Spiders don’t hunt humans; they don’t want to suck our blood. Nor do they want to eat any of our precious plants. All they want to do is hunt down and capture bugs, sometimes setting elaborate traps to capture them.
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If spiders are not an example of intelligent design, then such a thing does not exist. It would be amazing if all spiders only spun one kind of silk and all of them made the same kind of webs. Nothing could be further from the facts. Most people think of spider webs as the typical two-dimensional, spiral pattern screen created to catch flying insects. It should boggle the mind that a tiny creature that never had a course in engineering knows that anchoring only three points creates a flat plane of stability upon which to build such a net. Then they may place more anchor lines for added strength, but always in the proper position to maintain a flat plane.
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A spider web with droplets of dew in the tall grass looking like a diamond encrusted hair net is a beautiful sight. That web is designed with two very different kinds of silk. The radial arms are of a non-sticky kind that the spider knows are the safe lines to run along. The spiral strands are made from a very sticky formula even though they come out of the very same spinnerets. Some of the silk that the spider spins has very little to no elasticity when it needs a strong cable. But the sticky spiral strands have a chemical structure that lets them stretch quite a bit without breaking. All the better to enhance the tangling effect on the prey.
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Funnel web spiders build something entirely different. These spiders are a bit scary because they are quite venomous. It makes sense that they are, since their web is not designed to do any actual catching of prey. Like the spiral web, it serves as home, but that’s the only similarity. The funnel style is an elaborate surveillance network. The cave- like opening that is very apparent in the photo is barely visible enough to get your attention.
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The vast majority of the funnel web spider’s web stretches far beyond that opening and is very fine and delicate. The spider sits hidden inside it’s little lair reading and interpreting the signals that get sent down the line from creatures that are touching it’s amazing array of sensor wires. The spider can tell approximately how big the insect is and probably has it encoded in its DNA to be able to identify the exact species based on its movements. When the prey gets close enough to the entrance, the spider darts out and injects a lethal dose of poison, then drags the helpless insect back into the hole for dinner.
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The most common spider most gardeners will see is the wolf spider. Wolf spiders don’t seem to build webs of any kind. They crawl all over in the garden and tend to blend into their surroundings, only becoming visible when disturbed enough to move to safety. They chase down and capture their prey; they are the gardeners’ friend. Should you be bitten by a wolf spider, it is good to know that their venom is painful and irritating, but not having any long lasting effects.
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This is in great contrast to the spider that informed people fear most; the brown recluse or Loxosceles reclusa. This spider’s venom is so bad that a bite it causes necrosis in the flesh… It causes the skin, fat, and even muscle tissue to die. Should you be bitten by a brown recluse, seek medical attention immediately; this is no time for ”do-it-yourself” doctoring!
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Before you scroll down any farther, we must warn you that the pictures below are graphic. They show the results of bites from the brown recluse (also known as the fiddle head spider). If you are easily grossed out by such things, this is where you will want to exit the article or scroll past it very fast.
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The first picture shows the initial stages of blistering and decay from a bite.
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This is about a day after a Loxosceles ( Brown Recluse/fiddle head spider) bite with later stage necrotic damage.
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An example of having to have necrotic tissue removed prior to skin grafting. This damage was all from a Brown recluse spider.
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Okay, so that is why many of us don’t like spiders. But we should tolerate them and appreciate the fact that they provide a lot of good to our gardens.
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How do Spiders Eat?
Grass spider retrieving prey from her web
