White-Backed Garden Spider

Argiope trifasciata
Araneidae (orb weavers) in the order Araneae (spiders)

The female of this species is similar to its close relative, the black-and-yellow garden spider. However, the white-backed garden spider is slightly smaller overall, with a pointier hind end. Also, the abdomen is patterned with many thin silver and yellow transverse lines and thicker black, spotty lines. The carapace (head) is small and covered with silvery hairs. Males are smaller and thinner; they are usually only seen when courting or mating in the webs of females.

Length (not including legs): 1/2 to 1 inch (females); 1/8 to 1/4 inch (males).
Habitat and conservation: 
Webs are built in fairly open areas, such as in tall grasslands. Compared to the black-and-yellow garden spider, this orb weaver tends to position its web slightly lower in the vegetation. It also is less likely to be found in shade and is more tolerant of dry, open areas with sparse brush. Webs are large and wheel-shaped and built vertically. This species, like others in the genus, builds a stabilimentum, a thick zigag of threads, at the center of the web.
This spider eats a variety of insects, including grasshoppers, cicadas, and katydids. Once an insect is caught in the sticky strands of the web, the spider often shakes the web to make the insect more fully ensnared. Then, the spider further subdues her prey by injecting it with venom and wrapping it securely in sheets of silk. Often the spider repairs the damaged parts of her web before returning to her prey.
Distribution in Missouri: 
Statewide in appropriate habitats.
Also called the banded argiope. The genus name, Argiope, is variously pronounced ar-GUY-o-pee, ar-GHEE-o-pee or ar-JEE-o-pee.
Life cycle: 
Young spiderlings hatch in spring and disperse by ballooning on strands of silk that catch the breeze. Once mature, they breed only once, with the much smaller male courting by plucking strands on the female’s web. All summer, the females eat insects and create kettledrum-shaped egg cases 3/4 inch in diameter that can contain over 1,000 eggs each. Egg cases are generally attached to nearby plants. As temperatures cool in autumn, the female slows and dies in the first frosts.
Human connections: 
These spiders help control insect pests and are particularly appreciated by gardeners. Also, because of their colorful patterns, localized nature, remarkable web architecture, and easily observed behaviors, these spiders are excellent creatures for children and adults to watch.
Ecosystem connections: 
In addition to their role as predators, these spiders, and their young and egg cases, often are eaten by birds, snakes, and even praying mantises. In winter, birds such as chickadees and titmice hunt for spider egg cases. The nice big sacs of this species would be a feast!
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