Fall brings impressive spider webs

Walking outdoors can get a little sticky this time of year. That’s because the wheel-shaped webs of the big, nonpoisonous orb-weaving spiders seem to be all over the place —- stretched between shrubs and trees on hiking trails and garden paths or across porches, window frames and decks.

I counted four of the big webs with their sticky, velvety strands in my yard in Decatur the other morning: two in the backyard, one on the front porch and another in the front yard.

Actually, the orb webs are things to admire —- some of the greatest engineering feats of the natural world. Most species build their webs at night. First, a “bridge” is made between two “bridgeheads.” Usually, the spider sits with its abdomen in the air and lets the wind pull out a silk thread made of a protein that is one of the strongest fibers known. Once a bridge is established, the spider works steadily to build the entire web.

We see —- or run into —- these big webs in late summer and early fall because the spiders have matured and are completing their life cycles. The smaller webs that spiderlings built earlier in the year were mostly inconspicuous. But as the spiderlings aged, their webs became more specialized and characteristic of their species. To people, the average orb web is practically invisible, and it’s easy to blunder into one and become covered with its sticky material. (Spiders don’t get caught in their own webs because they have special hooked claws to grasp the silky threads.)

Once it builds its web, an orb-weaving spider ensconces itself in the center of the web or on its perimeter. An unfortunate insect that lands on the web struggles to get free.

To the spider, it means a meal has arrived. It immediately begins turning the captive with its first pair of legs and, with its fourth pair, wraps the victim in silk drawn from the spinnerets at the end of its body.

For a female orb-weaver, captured insects provide nourishment to produce egg sacs containing several hundred to thousands of eggs. The female dies soon after egg-laying. In some species the eggs will hatch soon; in others, not until spring.

Georgia’s largest orb weaver —- and one of its most common —- is the black-and-yellow garden spider, a member of the genus Argiope. The center of its large web is usually only about 3 feet off the ground. Other common orb-weavers building their distinctive webs now include:

>Barn spider, a nocturnal yellow and brown spider with striped legs. Like many other orb weavers, it takes down its web and rebuilds another web every evening.

> Basilica spider, which gets its name from the dome-like structure in its web that suggests church architecture.

> Golden silk spider, sometimes called the writing spider because of the occasional zigzag patterns (stabilimenta) in its web.

> Arrowhead spider, whose web may be anchored by a single silk strand 10 to 15 feet long, stretching between trees or posts.

FDR weekend

We went last weekend to the Warm Springs Historic Site in Meriwether County to swim in the naturally heated pools where the late President Franklin D. Roosevelt once sought relief from polio.

Stricken with poliomyelitis at age 39, Roosevelt started coming there because the water, naturally warmed to 88 degrees Fahrenheit as it bubbles up from 3,800 feet below the earth’s surface, supposedly had healing powers for a wide range of afflictions. Native Americans once used the water to speed the healing of their sick and wounded.

Roosevelt’s numerous visits to Warm Springs during his presidency made the area world famous. He built the Little White House on the edge of nearby Pine Mountain and died there at age 63 shortly before World War II ended.

The famous pools that he designed are now a state historic site managed by the Department of Natural Resources. The pools are kept drained to protect them, but each Labor Day weekend they are filled with the warm water and opened to the public.

As we enjoyed the water last weekend (and as FDR-era Glenn Miller tunes wafted from a loudspeaker), we easily imagined Roosevelt frolicking there with us. Warmed by heat from the earth’s core, the water contains minerals such as magnesium and sulfur and is said to be similar to Epsom salts in muscle-soothing qualities.

Roosevelt once noted that he could stand up —- and even walk around —- in three or four feet of the water without the use of braces.

In the sky

The moon is in first quarter tonight, high in the south at sunset, says astronomer David Dundee of the Northwest Georgia Science Museum. Mercury, Venus and Mars are low in the west just after sunset. Jupiter is high in the south just after dark and sets in the west around midnight. Jupiter will appear near the moon on Tuesday night.

seabrk@comcast.net