Spiders suddenly seem to be everywhere

Opposable thumbs? Who needs them when you have opposable fangs, and opposable claws. Not to mention the ability to make five kinds of silk, balloon through thin air to start a new life, and construct an architectural wonder every day.

Much maligned but endlessly talented, spiders seem to be everywhere at this time of year. From August until mid-October, spider watchers are deluged with calls from worried or amazed Puget Sounders.

"It's like clockwork," said Todd Murray at the Washington State University Cooperative Extension Office for Whatcom County. "It starts about August and will go to the first frost."

Spiders are always there, Murray explained. But they're more obvious now because they have been feasting on bugs all summer, and so are bigger, and building bigger webs to fit.

Welcome to spider heaven, as arachnid specialist Rod Crawford calls Western Washington. Crawford, volunteer curator at the Burke Museum for 30 years, said the region's diversity of habitats, abundant leaf litter and generous moisture make this prime spider country. And contrary to spiders' bad press, that's a good thing.

"Spiders are incredibly beneficial, we really encourage having them around," Murray said. "They are out there taking care of a lot of insect pests in our area. Without them we would be up to our armpits in flies."

Spiders have been around since before the dinosaurs. They are deadly effective predators that consume about half the extant insect bio-mass, Crawford said.

All spiders bite and are venomous — they kill their prey by injecting a dose of toxin with hollow fangs. But the amount and type of venom they carry is of little consequence to humans in nearly all cases.

The best response to the sight of a spider in the house or garden, Crawford advises, is "wave as they go by."

The spiders most visible right now are the abundant cross spider, a European invader that has successfully shoved many native species aside.

So-named for the white dots that form the shape of the Christian cross on its abdomen, the spider is a picture of elegance in its gossamer snare. Its slender legs sport alternating bands of deep brown and tan, its body intricately patterned in matching shades.

Like all orb weavers, as the spiders who create circular webs are called, the cross spider festoons anything from fences to window frames, garage doors and especially shrubs.

The cross spider will remake its web every morning, eating the old one to recycle the silk, excreting it from spinnerets on its abdomen for reuse within an hour. It takes not more than an hour to make a new web from scratch.

Orb weavers can make several types of silk: a sticky silk for catching prey in its web; a nonsticky silk used to wrap prey so it can't get away or bite back; a silk for binding egg cases; a drag line, for rappelling or walking about; and glistening ballooning silk, for surfing the breeze to colonize new territory.

While it looks delicate, the silk is stronger than nylon, and a marvel to scientists.

"It's a mystery how they secrete such long filaments," said John Edwards, professor emeritus of zoology at the University of Washington. "Chemists need high temperature and high pressure to spin a nylon thread, but spiders can do it on a dewy evening."

Outdoor spiders, such as the cross spider, are separate species from house spiders. They aren't trying to come indoors this time of year — that is a myth, Crawford said. Moving a house spider outside in fact may kill it.

Another myth: Spiders found in the tub come up from the drain. They were already in the house and are seeking water. Once in the tub they can't get out because of its smooth sides.

House spiders are most visible in August and September, when their mating season drives males into the open in search of a mate.

Even the giant house spider — which can span four inches, tiny foot to tiny foot — are beneficial and shouldn't be swatted, entomologists say.

That is in part because they best the hobo spider for indoor habitat. The hobo spider's bite can be harmful to humans. The brown recluse spider, which also packs a harmful bite, does not live in this region.

While the mating season for house spiders ended in September, the cross spider is just now laying its eggs. Mating is a dicey business for the males, who are only 20 percent of their mates' size. The risk of becoming a meal is high.

The male's usual strategy is to pluck the female's web to announce his arrival, then to rappel out of sight on his drag line until the female's receptivity is clear. As soon as she is mated, the male pays out another line and gets out of Dodge.

Females deposit as many as 900 eggs on a silk platform, then wrap the eggs in a silk purse. Spent with the effort, they usually die soon after.

Most spiders live only a year. Some tarantulas are an exception, living as long as 25 years.

Cross spiders' eggs will hatch within 10 days to two weeks. The spiderlings bide their time within the egg sack through the winter.

If you open it, you'll wake them and they will wave their tiny legs. But, left alone, they will emerge in May, a new generation of weavers, ballooners and crack insect exterminators.

Lynda V. Mapes can be reached at 206-464-2736 or lmapes@seattletimes.com.