How Many Spiders In Garden Spider Egg Sac

Black and Yellow Garden Spider

(Argiope aurantia)

Black and Yellow Garden Spider

The Black and Yellow Garden Spider lies in wait for an insect to get stuck in the web.

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Range

Commonly found in the United States, Canada, Mexico and Central America.

Description

The Argiope aurantia is an orb web spider. Orb web spiders spin their webs in a circular pattern. The common names used for the Argiope aurantia are black and yellow garden spider, writing spider, banana spider and corn spider. This spider is not harmful to humans.

Males .2 - .35" in
Females 75 -1.1"
4 pairs legs with yellow, red or orange coloring towards top of legs near the abdomen
Each foot has 3 claws
Oval-shaped abdomen that is black with yellow or orange markings
Short, light-colored hair on cephalothorax (forward section of the body)

Habitat

Black and yellow garden spiders often live near open fields in higher brush and vegetation. They are also found in gardens and eaves on houses and buildings. They select areas that are sunny with little to no wind.

Webs may span up to two feet in diameter. They are round in shape and are made anywhere from 2' to 8' above the ground. The web of the garden spider is distinct. The web has a dense area of silk towards the center of the web that forms a zigzag pattern called the stabilimentum. The purpose of the stabilimentum is debated. It may be used as a camouflage, to warn birds of the web's presence or to attract prey. The presence of stabilimentum is only common to spiders that are active during daylight hours.

Web of spider

Webs of the Argiope aurantia may span up to two feet in diameter.

Behavior

The male garden spider usually constructs its smaller web next to or nearby the female's web. The female's web tends to be larger than the male's, and it can be identified by the Z-shaped, vertical line in the middle area of the web. The females typically stay in an area and often use the same web for an entire summer season, while the males roam.

The spiders hang out near the center of the web waiting for prey to get caught in their web. If predators are nearby, the spiders may retreat into nearby bushes or onto the ground to take cover.

Every day the spider eats part of the interior portion of its web and reconstructs it with fresh silk. It is believed that the portion of the web that the spider consumes may contain small nutritious particles such as tiny insects.

Diet

Spiders are carnivorous. The larger female black and yellow spiders can consume prey up to 200% of their own size, although they prefer smaller creatures (Feeding ecology of the orb-weaving spider Argiope aurantia [Araneae: Araneidae] in a cotton agroecosystem, Nyffeler et al. 1987). The main diet of the yellow garden spider consists of flying insects such as aphids, grasshoppers, wasps (some species), bees, and flies. They lie in wait, normally in a head-down position towards the center of their web, for an insect to get stuck in the sticky silk portion of the web. The spider then creates an undulating motion that helps further trap its prey. The prey is then paralyzed when the spider injects it with venom. The spider spins a silk sac around the dead insect to save it while it continues to hunt. The spider will consume the dead insect at a later time.

Reproduction

Yellow garden spiders breed once a year. The female produces from 1000 to 4000 eggs in multiple sacs (from 1 to 4). The egg sacs are brown in color and made of silk. The female most often attaches the egg sacs toward the center of the web, where she can easily guard them. She guards her eggs until she dies, usually around the time of the first frost. Males die after breeding, and are sometimes eaten by the female spiders. The eggs hatch in the late fall/winter and the young hatchlings remain in the sac until spring. When the eggs hatch in the spring, the spiderlings, which are very tiny, disperse. Some travel in the wind using a strand of silk web to fly them in the air, while others stay in the area to hunt and build their own webs.

Predators

The yellow and black garden spider has many predators including birds, lizards, shrews and a few species of wasps. Humans are also predators.

Interesting Facts

The word "aurantia" comes from the latin word "aurantium" which means orange, the fruit.
Yellow garden spiders may bite if harassed, but they are harmless to humans.
When threatened, the black and yellow garden spider will vibrate the web to make them seem larger than they are.
The stabilimenta, or zigzagged vertical area of the web, resembles writing which has earned this spider one of their common names "writing spider."

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