Quite often even people with arachnophobia are not unduly afraid of garden spiders. Perhaps this is because they are large, colorful and relatively calm spiders. After all, encountering one sedately sitting on its web in the tall grass meadow is hardly comparable to turning on the garage light to see a large wolf spider scurrying across the floor. The Golden Garden Spider (Argiope aurantia) is the best known of the garden spiders. These spiders spin flat, circular webs in tall grass, weeds, or shrubbery, quite often in a garden setting, usually at eye-level or below. Because they are diurnal, they spend the daylight hours patiently sitting, head downwards on the center of their web and are frequently seen.
The web may be 18 inches or more in diameter and constructed of silk that the spider
secretes from special silk glands on the abdomen. The web is always decorated with a vertical zigzag pattern at the center and is often the first thing that you notice. I don’t think naturalists are completely in agreement as to the purpose of that “signature”. Earlier this summer I started asking my naturalist friends to keep an eye out for Garden Spiders so that I could photograph them and pass this on to you. Every year in spring and early summer they don’t seem to be around, however, by late summer into fall they seem to be everywhere.
A spider’s body consists of two major parts, or segments. The cephalothorax (combined head and thorax) has the brain, eyes, poison glands, mouthparts, and stomach. The larger abdomen contains the heart, gut, lungs, reproductive organs, and silk glands. Spiders have four pairs of legs. Insects, you will remember, have three body parts: head, thorax, abdomen, and antennae, three pairs of legs and often wings. Some insects have silk glands as well, for example, tent caterpillars and silkworm larvae. Spiders never have antennae or wings. Spiders have four pairs of eyes. The size and placement of the eyes on the cephalothorax is a key identifying feature for each species. Although the Golden Garden Spider is reported to have weak vision, it can detect the slightest vibration or change in tension of its web. Other spiders have excellent vision.
The jumping spiders have some of the sharpest vision of any arthropod with
two large forward facing eyes flanked by three pairs of smaller eyes along the
front edge of the cephalothorax. The nocturnal wolf spiders have good night
vision to locate and catch prey in darkness.
Spiders can spin various types of silk depending on the species and purpose the
silk is used for. Garden Spiders spin strong, non-sticky strands to create the
supporting guys and stays of their web that is attached to branches or other
vegetation. The radiating spokes are spun using basically the same silk. The spiral
net is formed of sticky silk. Finally, the Garden Spider places a zigzag spun of
much coarser silk at the center of the web. This is sometimes called the
“signature” and gives the group its folk name. Different species of Garden Spiders
have differing signature patterns (see photos).
The owner rests head downward on that spot patiently waiting for some insect to get ensnared. (Just how spiders construct their web will be discussed in more detail in a later article).
The Garden Spider is very sensitive to the slightest vibration. Sometimes when you approach the spider may bounce the web vigorously up and down like a trampoline. The purpose may be to further entangle a victim, or it may be simply to scare away an enemy. When an insect gets entrapped in the web, the spider quickly and accurately runs to the exact spot (never getting tangled up itself). The prey is grabbed with the front pair of legs and rapidly rolled over and over while the fourth pair of legs spreads out a sheet of special wide wrapping silk being secreted by the spinnerets; the insect is spun around and around until it is completely enshrouded.
I have seen spiders pause for a moment or two in the process and if the prey continues to struggle, wrap a few extra layers on the captured insect. Once the insect is completely immobilized, keep in mind that a spider has a soft body and a large insect such as a grasshopper could do serious damage to it, the spider bites with its fangs through the shroud and kills, or paralyzes the insect. After a short while if the spider is hungry it may begin to feed.
The spider’s venom not only kills the insect but serves to liquify the body’s contents and the garden spider sucks the exoskeleton dry. Or, if the spider is not hungry in times of plenty, it carries the neatly wrapped package to the edge of its web and safely hangs it there as a meal for leaner times.
If you are observant, you may notice these pre-packaged meals hanging in the webs. Once all the nutrients are extracted, the insect, shroud and all, are carried to the edge of the web then unceremoniously dropped to earth.
When I was a boy here on the Tantrough farm where I live, I was fascinated by all this process. For some reason there was always an abundance of Garden Spiders directly behind my grandmother’s poultry house, probably because of the sheer numbers of insects that were active there, flies, moths, wasps, grasshoppers, etc. This low wooden structure was about 100 feet long and often there were as many has six occupied webs there.
Since I had the daily chore of filling the wooden half barrel trough for the cow using the cast iron #2 Deming hand 0perated pump (all water for the livestock was pumped from the well by hand with what was called a “pitcher pump”). I would sneak a few moments to visit my spiders behind the nearby poultry house, catch a few of the small red-legged grasshoppers, my favorite size for this adventure, in the tall grass and carefully flip them into the webs. Very often the grasshopper fell completely through and escaped. No matter, I could always catch dozens more. Eventually one would get snagged, and I was amazed at the speed and efficiency that the spider took care of business, from beginning to end perhaps no more than 30 seconds to a minute. So, I felt that I was helping to rid the garden of pests that ate our string beans and tomatoes plus we had the fattest Golden Garden Spiders in Milford.
As the chill winds of Autumn begin to stir, the much smaller males seek out the females to mate. The male dies shortly after mating. The female deposits her fertilized eggs on a little pad of silk. As a final protective layer, she wraps it all in a tough layer of weather- proof tan silk. This is left hanging on the web and the female dies shortly thereafter, too. Some of the eggs may hatch in the Fall, however, others will not emerge until the following Spring. I am certain that some of the Garden Spiders I see today are direct descendants of those I fed as a boy.
N.B. I was pleased to meet three generations of our newest readers on the trail
that have been enjoying the Nature Preserve trails for twenty-seven years.
Greetings and Happy Hiking!
Recommended reading: Spiders and Their Kin, by Herbert W. Levi and Lorna R.
Levi, A Golden Nature Guide