Broadcast: February 8, 2005
I'm Gwen Outen with the VOA Special English Agriculture Report.
Spiders kill more insects than they can eat. And most spiders can eat up to two times their body weight in insects each day. So, if you want to keep harmful insects out of your garden, invite a few spiders to live there.
That was the advice given some years ago in the magazine Organic Gardening, published by the Rodale Institute. Spiders do eat both good and bad insects. But Professor Susan Riechert at the University of Tennessee in Knoxville said spiders eat more harmful insects than helpful ones.
Professor Riechert said spiders will remove from sixty to eighty percent of the insects from a garden. But, she added, if you want spiders to live in your garden, you must not use chemicals that can kill them.
Here are short descriptions of nine different kinds of spiders that live in gardens.
Orb weaver spiders make huge sticky webs between plants. When an insect enters the web and is trapped, the spider attacks.
Sheet-web weavers make flat webs. The spiders stays under the web. When an insect lands on top of the web, the spider reaches up and pulls the insect through to the bottom.
Mesh-web weavers make tiny webs inside small openings in a plant's skin. This spider eats mainly aphids.
Combfooted spiders trap insects in their webs. Then they wrap their catch inside more web material.
Funnel-web weavers build circular webs that are wide at the top and closed at the bottom. When an insect lands on the web, the spider jumps out, catches the insect and drags it back inside the funnel to eat it.
Wolf spiders do not use webs to trap insects. They live on the ground among the leaves. They eat aphids, leafhoppers, flies, beetles and grasshoppers.
Jumping spiders also do not make webs. Their meal might include a spotted cucumber beetle, a corn earworm, or a bottom bollweevil.
Lynx spiders will spin some silk to seize an insect. But they, too, do not make a web. They like to eat fire ants.
Crab spiders move sideways, just like crabs in the sea. Crab spiders do not make webs. They wait quietly for an insect to come near and then they capture it.
Internet users can get more information about Organic Gardening magazine on the Web at organicgardening dot com. (organicgardening.com)
This VOA Special English Agriculture Report was written by Bob Bowen. I'm Gwen Outen.