Your garden is part of a diverse ecosystem complete with its own food chain. Spiders are an integral part of this "eat and be eaten" system. Spiders do not eat plants, so they pose no threat to your foliage. Instead they help rid your garden of leaf-eating pests. In return, they are food to other creatures that venture onto your property.
Airborne predators happily snack on your garden arachnids. Blackbirds, robins, chickadees and crows are examples of feathered visitors that will keep your spider numbers in check. Even larger rodent-eating birds such as owls eat spiders. Spider wasps have no mercy on garden spiders: The female wasp paralyses the spider and digs a hole in which she puts the immobile arachnid, alongside one of her wasp eggs. The baby wasp hatches and eats the paralysed spider.
Land creatures also prey on spiders. These include other insects, rodents and amphibians. Shrews, opossums, skunks and even the household cat catch and eat spiders. If you live in an ecosystem that sustains frogs, expect them to eat your garden spiders as well. Centipedes use venom claws behind their heads to sting and paralyse spiders before eating them. Ticks attach themselves to spiders and eat them as the spiders carry on living and moving.
Spiders are an important terrestrial predator and benefit your garden. Because they will eat almost any type of insect they can catch, they help rid your garden of a diverse number of plant-eating pests. They position their webs to trap plant-eating bugs as the bugs travel from leaf to leaf. Once an insect has been trapped in the spider's web, the spider stings the insect, wraps it in silk and waits for it to die. It then vomits digestive juices onto the bug and consumes the digested insect flesh. It continues eating this way until all that remains are the insect pieces that are too hard for the spider's expelled digestive juices to dissolve.
Protect your garden spider population. Leave intact any webs you may find. Feed your spiders by lighting areas of your garden at night to lure other insects for the spiders to catch and eat. Purchase spiders for release into your garden. Deter birds from approaching your garden with ornaments that resemble their predators, such as owls and snakes. Prevent bird access with barriers such as row covers or netting. Try a motion-activated sprinkler to deter terrestrial visitors, such as cats and rodents.
- Colorado State University Extension: All About Spiders; Dr. Linda S. Rayor
- Washington State University Extension: Protecting Strawberries from Birds; August 1996
- Capital District Community Gardens: Garden Pests and Diseases
- University of California Statewide Integrated Pest Management Program: Common Garden Spiders
- Fairfax County Public Schools: Black and Yellow Argiope
- Tooter 4 Kids: What Does an Owl Eat?