‘Tis the Season for Spiders

E.B. White’s Charlotte Web was my favorite childhood book, and I’ve loved spiders and pigs ever since. Luckily my husband also shares my passion for our non-human creatures. When summer comes, this means we get to roam our property at night with flashlights and especially watch the female orb weaver spiders – Charlotte was an orb spider – spin their webs and over the weeks, grow larger before laying eggs in the fall.

One early fall we even got to witness a tiny male – they’re always dwarfed in size by the female – use his legs to vibrate the edge of the web to announce his presence. In this case the female accepted his invitation. They mated despite their disproportionate sizes, and when we came back, the male had disappeared. We don’t know if he left or she ate him, which sometimes is the case. But by that stage in her life, she was huge and not eating much. As with Charlotte, she produced her last clutch of 100 or more eggs, and not long afterwards curled up and died. After decades of spider research, Rick Vetter from UC-Riverside’s entomology department recently learned that instead of the eggs overwintering, the babies hatch out after a few weeks. “The babies stay inside the egg sac until the following spring or early summer,” says Vetter. And then the cycle repeats once again.

I’m always a little perplexed with the number of people who are arachnophobic, afraid of spiders. So it’s with joy that I write about common spiders that are gracing our yards this summer. Vetter also cleared up some spider misconceptions.

“Most verified bites by medically benign spiders leave a little red mark, a little swelling, a little itching and then it all goes away by itself.”

Debugging Spider Myths

First, though, why should we re-think our impulse to step on a spider when we see one? Except for two types of spiders in North America, bites from spiders are rare, minor and overblown. Historically, medical practitioners have mistakenly blamed spiders for many skin lesions, when many misdiagnosed spider bites are bacterial infections. “Most verified bites by medically benign spiders leave a little red mark, a little swelling, a little itching and then it all goes away by itself,“ says Vetter.

Here’s other information, followed by two spiders you have likely seen in your yard or neighborhood:

• Spiders are beneficial because they prey on a large number of insects, including pest species. They’re also a common food source for other wildlife, such as lizards and birds.
• Spiders avoid humans and pets. Active at night, they’re shy and usually remain hidden in undisturbed areas, and try to escape when disturbed.
• Most not harmful: There are only two medically important spiders in North America, widow and recluse spiders: A large percentage of people have moderate to severe reactions from widow spiders, although the bite of the brown widow spider, which has expanded westward, appears to cause less reaction. As for recluse spiders, some people react severely to their bites but research shows most are minor and temporary.
• Terminology confusion: While most spiders are venomous – they deliver venom to paralyze their prey – except for the two above, their venom is not harmful (toxic) to humans.

  

• It’s unnecessary to eradicate all spiders from a home. Because of their beneficial nature, they play an important role. Tolerate spiders whenever possible or relocate them outside. (It’s easy. Find the least squeamish person in your home and give them a plastic cup and stiff card.) When tolerance is not possible, use an integrated approach that considers non-chemical methods.

Prowling for Orb Spiders

When author E. B. White wrote Charlotte’s Web he consulted spider books to accurate portray the life cycle of Charlotte, an orb weaver spider.

Some things to ponder as you’re watching an orb spider:

• Of all the families of spiders, they vary the most varied in appearance and size (1/4 to over one inch), which helps explains why I’ve seen such variety in our yard.
• Their webs consist of concentric circles, smaller ones within larger circles, with anchor lines to structures, bushes, outdoor furniture or the ground.
• Some leave their web intact, but nearly all of ours eat their web’s silk before dawn, which also gives them moisture, and rebuild it again the next night. Juveniles start out with perfect, beautiful webs but we’ve noticed towards the end of the spider’s lives the webs get a bit, well, wacky.

• Sometimes they take a day off after a good feast of prey. Some evenings we make the rounds and throw them a grain moth (that over 12 years we haven’t been able to eradicate from our parrot seed mixes) and watch them bite the prey, wrap it in silk while it dies, and then eat it by sucking out the insect’s juices.
• Most importantly, orb spiders are very docile and not a danger to people or pets, and will try to escape if threatened. My husband got a rare bite when he wrapped a towel around him that contained a sleeping orb spider. It felt like a bee sting, and they both survived.

Lowering Your Sight for Funnel Spiders

Funnel spiders are another favorite. Commonly called grass spiders because of their location in the grass or in bushes, they lay down a horizontal, sheet-like web with a small funnel-like entrance either in the web’s middle or side.

Other interesting things:

• Funnel spiders lay in wait in or near the funnel, and rush out quickly if an insect lands on the web. If it’s prey, they bite it with a fast-acting venom. After a second or two, the spider drags the prey back into the funnel to safely eat it, which also prevent other insects from seeing what happens when you land on that web. There are over 100 species in North America.

  

• One misconception is that bites from funnel spiders in the U.S. are dangerous. There are some funnel-web spiders in Australia that have toxic venom for humans and are featured on Deadliest Spider type documentaries. However, these are different from the funnel spiders found in the U.S., and except for rare reactions are harmless.

Go outside with a flashlight one of these evenings and see what you can find. But watch out for the anchor strings of the orb spiders – they depend on those to keep their webs so nice and concentric.

For more info:

Bug Guide – http://bugguide.net/node/view/2001

RickVetter’s website