Dani Barchana, Bugwood.org
Banded garden spiders are not as commonly encountered in Pennsylvania as yellow garden spiders, although they inhabit similar locations. Where the habitat is favorable, this spider is found throughout the United States.
Argiope trifasciata female. Photo by Jorge Íñiguez Yarza, Flickr
Argiope trifasciata (ventral). Photo by Curtis Michael Eckerman, BugGuide.net, photo# 34401
The banded garden spider female is 15 to 25 millimeters in length—slightly smaller than the yellow garden spider. The carapace is covered with silvery hairs. The abdomen is an elongated oval with the posterior somewhat point-ed and the anterior rounded without the humps or notch described in the yellow garden spider. The abdominal background color is a pale yellow/silver with numerous lateral bands or stripes of black. The legs are also a pale yellow with darker spots or bands.
The males are 4 to 5 millimeters in length and their abdomens are mostly white. The immature banded garden spiders also have a mostly white dorsal surface of the abdomen. The egg sac is similar in texture and color as that of the yellow garden spider, but it is shaped more like a kettledrum.
The web is similar in size and shape to that of the yellow garden spider. It is not uncommon for the stabilimentum to be absent or have variability in shape.
Banded garden spider adults can be found from mid- to late summer through the first freeze. Egg sacs are deposited in early fall and consist of several hundred eggs. The immature spiders emerge the following spring.
A behavioral study of web construction determined that the majority of Argiope trifasciata orient their webs along an east-to-west axis. The spiders hang head-down in the center of the web with their abdomens facing south. Since the underside (venter) of the spider is mostly black, the orientation of both web and spider is believed to maximize solar radiation for heat gain—an important consideration for spiders that are active late in the year.
Similar to yellow garden spiders, banded garden spiders are not known to be medically important. It is unlikely that bites would occur unless people handled a female with an egg sac in the web. Even then, the bite would likely cause no more discomfort than a wasp or bee sting in most individuals.
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