Spiders, Scary or Beneficial? Monday April 1, 2013
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Spiders

Spiders are predators and almost all carry venom but their purpose is to kill insects, not attack humans. Whether spiders create webs for catching prey or dig burrows with trap doors, or hunt by chasing insects over short distances, their goal throughout the day (like some of us humans) is to – eat.  Many spiders are beneficial outside of the home where they eat ants, crickets, flies, sow bugs (roly-polies), aphids, and other insects. Inside, spiders will help eliminate termites but most people prefer not to share the same living space with these arachnids!

Green Lynx Spider(Peucetia viridans) with egg sac on a Sycamore tree in Escondido, CA

Green Lynx Spider(Peucetia viridans) with egg sac on a Sycamore tree in Escondido, CA

Scary or Beneficial?

What happens when you do see a spider? Does the heart start racing? Feel the need to immediately eradicate it with one fell swoop of a shoe? You´re not alone; most people can´t stand spiders. Spiders are often a source of an irrational psychological fear commonly known as Arachnophobia (wonder what it was called in prehistoric times….?)

Face of Green Lynx Spider

Face of a Green Lynx (check out the hairdo) Is this a face to be afraid of?

For those less affected by spiders, they still cause a slight to severe dislike when encountered. It could be that for most people, the surprise of seeing a spider, all of a sudden where you least expect it, is what´s so “scary.”

Orb-weaver, Garden Spider

The Garden Spider is an “Orb-weaver,” a beneficial Arachnid in garden Landscapes.

As more people are “Going Green” and are concerned about nature, many are beginning to see the beneficial aspects of spiders. In the outdoors, they act as natural pest control agents, ridding gardens of pesky pests that destroy plants and shrubs. Did you know…..spiders eat about 2000 insects per year? The perfect “orb webs” seen outside are made by Garden spiders and are designed for catching those pesky garden insects.

spider in amber

A spider in amber; the bubbles indicate that the spider was alive when it became trapped.

Prehistoric Spiders

There are over 40,000 species of spiders throughout the world, with many more still unnamed. The oldest “true” spiders are about 300 million years. These early spiders had spinnerets (an organ for spinning silk) under the middle of their abdomens; modern spiders´ spinnerets are at the end of their abdomens.

Spider Spinnerets weave silk for webs

Spinnerets on a modern day Barn spider.

Initially, spider webs were just to encase the eggs but by the Jurassic Period, the sophisticated webs of Orb-weaving spiders developed significantly into large, intricately woven webs. These larger webs enabled spiders to take advantage of the unending supply of insects.

Yellow Garden Spider

Yellow Garden Spider – Orb Weaver

The Hunters are also Hunted

Some spiders are active hunters rather than web-builders; like the Wolf spider, it hunts down and even chases its prey. Then there is the Trapdoor spider that makes a burrow in the ground with a web-hinged door and when a cricket or bug passes, the spider pushes the door open and pulls the cricket inside with its strong mandibles.

Illustration of a Trapdoor Spider by Donna Walker

Drawing of a Trapdoor Spider Catching a Cricket

However, spiders often become the hunted, by birds, lizards, and certain wasps like the Mud dauber or Spider wasp. These wasps paralyze the spider to keep it alive and fresh for feeding larvae after they´ve hatched.

Mud dauber wasp

Mud dauber wasps hunt spiders to feed to their young.

Keeping Spiders Outdoors (where they belong)

Repellents won´t necessarily keep spiders away because, unlike insects, spiders are not as affected by the residue pesticides leave behind. However, using pesticides, whether traditional or organic, gets rid of the insects – a spider´s food source.

The best prevention is knocking down webs, regular sweeping, vacuuming, keeping corners clear, checking under patio furniture for webs, sealing off any cracks or gaps where spiders can get in, and treating for insects – eliminating the food source.

The reality is, spiders have been around for a long, long, time and they will not be going away any time soon…..webs will continue to be built, and humans will continue to swat them down. Maybe, just maybe, the next time you come across a spider, especially outdoors, you´ll take a closer look and come to appreciate these amazing creatures. But if the spider is, in fact, a Black widow……..
I totally understand if you use that shoe!

Black Widow Spider

Black widows spiders are toxic to humans; the red “hourglass.” defines the Black widow.

NOTE: The California Poison Control Center indicates that not all black widow bites require medical attention but provides the following reasons to go to the doctor if you do suffer from a bite:
o Discomfort which is increasingly severe.
o Spreading local redness accompanied by pain.
o Any drainage from a bite site.

Article and Illustration by Donna Walker

Coming Soon……..Spiders Portrayed in Various Cultures

Dream Catcher

Native American Dream Catcher

References

California Poison Control Center
National Pest Management Association – PestWorld.org
Wikipedia – Spiders; Garden Spiders
Mallis, Handbook of Pest Control, Tenth Edition, Saunders College Publishing, 2011.

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