There are more than 3,000 types of spiders in North America, including the crab spider, jumping spider, wolf spider and orb-web spider. These eight-legged predators will eat all kinds of insects in your garden.
Illustration By Keith Ward
This article is part of our Organic Pest Control Series, which includes articles on attracting beneficial insects, controlling specific garden pests, and using organic pesticides.
Garden Spiders (Aranea)
Unlike insects, spiders have eight legs rather than six, and they probably are the most abundant predators in home landscapes. Arachnologists estimate that at any given time 100 to 200 spiders live in an average house; about 10,000 spiders live in one acre of typical forest habitat; and between 1.5 and 2.5 million spiders can be found in an acre of grassland.
Any garden will be home to several dozen types of spiders, and the most common garden spiders do not spin webs. Wolf spiders are the brown spiders with dark stripes that gardeners often disturb when raking up mulch or renovating garden beds. Females often carry their egg sacs with them, scurrying to find cover when disturbed. For two weeks after her eggs hatch, the mother spider carries her young on her back. Wolf spiders live in shallow underground burrows, and are very common beneath mulch.
Also common in gardens, jumping spiders do not make webs, but do use a string of silk to tether themselves to vegetation in case they miss a jump. These energetic spiders hunt during the day by pouncing on prey, which often includes flies and other small winged insects. A recent study found that jumping spiders are able to learn colors associated with prey. If they accidentally jump on your shoulder, the color of your shirt may be perceived as a happy hunting ground. Blow them off if you don’t like their company.
Crab spiders have oversized front legs, giving them a crablike appearance. Often called flower spiders, crab spiders hunt during the day by ambushing small insects. Perhaps in response to reflected light, many crab spiders are able to change color to precisely match the flower they have chosen as a hunting perch.
What Do Spiders Eat?
While web-spinning spiders consume whatever they catch, recent research from Texas suggests that many jumping spiders, crab spiders, wolf spiders and other garden spiders are not indiscriminate diners, but in fact develop rather narrow tastes in prey. For example, a crab spider may stay on a certain flower after it learns how to capture insects that visit that blossom. Wolf spiders wander the soil’s surface by night, or simply wait by their burrow for unsuspecting insects or slugs.
How to Attract Spiders to Your Garden
Spiders are naturally attracted to the good hunting available in a diversified garden. Perennial herbs that grow into lush bushes often make good spider conservatories, and biodegradable mulches like grass clippings create an ideal habitat for wolf spiders. Give spiders a few minutes to run away when renovating expired plantings or pruning large bushes. Avoid using pesticides in the garden, which are usually lethal to spiders.
More information about garden spiders is available from Colorado State University, University of California, University of Michigan, and the University of Kentucky.