Orb weaver spiders construct the familiar circular, flat, elaborate web in which flying insects are trapped. Each species of orb weaver typically constructs a web with a distinctive design. Webs usually occur outdoors. These spiders have poor vision and locate their prey by feeling the vibration and tension of the threads in their web. They use silk to wrap the victim.The University of Illinois adds, "The orb weaver produces an oil in its mouth and spreads this oil on the body, preventing it from sticking to its own web. They paralyze their prey with venom and then crush it with their pedipalps (a set of mouthparts.) Once the prey is crushed, the liquids in its body are consumed. Spiders mate by males spinning small webs that they place sperm in, and then transfer the webs to the female."
Many species of orb weaver spiders are large (approximately 1 inch), but others are quite small (approximately 0.1 inch). Some have oddly shaped abdomens (pointed spurs, conical tubercles, etc.). Some are very brightly colored. One common spider, known as the yellow garden spider (Argiope aurantia), has silver hairs on the back of the cephalothorax and a large abdomen marked in black and bright yellow or orange. This spider is about 1 inch long and hangs head down in the center of the web, which is found in brambles, bushes, tall grasses, etc. in open sunny places.
Despite their formidable appearance, orb weaver spiders are not considered dangerous. Some species can bite if handled.
Previous encounters with these beneficial arthropods can be found here and here.