September 2015

Garden spiders add color and drama to the landscape

A garden spider spins a silky tomb for a bumble bee. © Jo Ellen Meyers Sharp

A garden spider spins a silky tomb for a bumble bee. © Jo Ellen Meyers Sharp

This time of year, garden spiders spin their orbs in the landscape.

The yellow and black females are larger than the males, more colorful and usually more visible, especially this time of year. The females make the large webs, some up to two feet across, and the males spin smaller orbs around the fringes, each with a zigzag in the center.

The garden spider (Argiope aurantia) is native throughout the United States and is considered a beneficial insect.

The female garden spider is about one inch long, but is not harmful to humans. She hangs upside down on her web, spun between two plants in a sunny spot protected from wind. The male is narrower and may be brownish. It is about one-fourth to one-third inch long.

When bees, flies, butterflies and other insects become ensnared in the web, the spider shoots them full of venom and quickly wraps them into silky tombs. Some are stored for dinner later, but many are eaten as soon as they are encapsulated. Each day, the female garden spider eats the entire center section of the web and spins a new one. Speculation is she cleans out her pantry of bugs to make way for the new catch of the day.

Late summer is the annual mating and egg-laying season. So risky is his journey into her web that he frequently has a silken tether at his belly that allows him to drop to the ground if she says no. The males die after mating and sometimes make a meal for the female.

She lays her eggs and wraps them into round bundles of silk, with the last layer a brownish color for better camouflage. She hangs the egg sacs on the web where she can guard them against predators. She usually dies by the first frost.

Eventually, the eggs hatch, but stay in their cocoon until spring when they emerge and go their way.

The Fairfax County (Va.) Public School’s Web site has more lifecycle details and other interesting tidbits about this spider.