The yellow garden spider Argiope aurantia (Family Araneidae) is a common inhabitant of roadsides, pastures, and forest edges throughout north central Texas. This strikingly colored spider builds its orb web on supporting structures (barns, fence posts) and vegetation (shrubs and low trees). The web includes a central hub where the spider waits for prey. Prey are captured on the catching area of sticky silk which surrounds the hub. Preferred prey include grasshoppers and moths. When a prey item lands in the web, the spider runs quickly out from the center of the hub and grasps the prey with front legs, then wraps the prey with silk, using the back legs to draw out strands of "swathing" silk, which is different in structure from web-building silk. The spider then bites the prey to inject venom, and waits for the prey to die before consuming it.
Spiders are members of the arthropod subgroup "chelicerates", which means their primary food-handling appendages are "chelicerae", as opposed to mandibles in other arthropod subgroups. The secondary food handling appendages are "pedipalps", which are relatively small and "palp-like" in the spiders, but are large and claw-like in scorpions and their relatives. The chelicerae of spiders are typically modified as fangs, or sharp and pointed hypodermic syringes for injecting venom into prey. Yellow garden spiders have fang-like chelicerae, but they appear to use them only to bite prey and not humans or other vertebrates that disturb their webs.
The central part of the orb web of members of the genus Argiope is often adorned with a zig-zag pattern of swathing silk. This structure is called the stabilimentum, because it was once thought to stabilize the web. Its function is a subject of current scientific research. Hypotheses for its function include 1) a signal to birds or other vertebrates to reduce damage to the web, 2) a hiding area for the spider, and 3) an attractant for insect prey (because it reflects ultraviolet light). Which of these hypotheses (if any) is correct is unknown.
This time of year, the large spiders are females, and they are busy eating prey and converting the prey into spider eggs. The female spiders produce one to several egg cases, which they typically hang in vegetation (or other structures) near their web. These egg cases contain several dozens or even hundreds of eggs. The eggs hatch in the spring to release spiderlings, which begin to build small webs and catch prey. Once male spiders mature, they begin to visit females' webs to attempt to mate. I have not heard reports of sexual cannibalism in Argiope, but the males typically do not survive past mid-summer. The females continue to grow and lay eggs into September and October, but they do not survive the winter.
The characteristics of the webs change in a regular fashion as the spiders
grow. The height and width of the entire webs become larger, as do the
height and width of the hub. The stabilimentum also changes, but in a less
regular pattern. Older webs often have only one "arm" of the stabilimentum,
below the center of the hub, whereas younger webs usually have both upper
and lower arms. The spiders generally build their webs farther from one
another as they grow. Mortality appears to be significant, as population
density declines as the summer progresses.