Grasshopper damage can devastate organic gardens, particularly in areas with hot, dry weather. Learn how to use floating row covers and other techniques for effective natural grasshopper control.
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.
Wherever you find grass, you will also find grasshoppers, and a few of the hundreds of grasshopper species found in North America can be major garden pests. Cool, rainy summers cause many grasshoppers to fall prey to disease, while hot, dry weather can lead to major grasshopper headaches.
Grasshoppers weaken plants by removing plant tissue, and they are especially damaging to lettuce, beans, corn, carrots, onions and cabbage family crops grown for fall harvest. Organic controls for grasshoppers include excluding them with row cover or screen barriers, controlled poultry predation, and inoculation of the soil with microorganisms that kill young grasshoppers. Grasshoppers are found throughout the world, and are most problematic in areas where wild grasses dry up in summer, causing the hoppers to move to lush, moist gardens.
Ancient insects that have inhabited Earth for more than two million years, plagues of grasshoppers have been responsible for many famines. More typically, grasshoppers fly into gardens in late summer and chew up plant leaves.
Ragged holes in leaves, especially those near the tops of the plants, are often the work of grasshoppers. In severe situations, masses of grasshoppers can appear suddenly in late summer and devastate gardens.
Most grasshoppers overwinter as eggs laid by females in late summer and early fall, though a few species survive winter as young nymphs. Baby grasshoppers hatch in spring and early summer from eggs hidden just beneath the soil’s surface. Young grasshoppers hide out in sheltered spots that are dense with vegetation. Only older, mature grasshoppers can both jump and fly, which they will do in order to find new food sources.
Depending on species and weather conditions, a female grasshopper can lay up to 2,500 eggs before she dies at the end of the summer. Most of these are placed in dry, grassy areas outside the garden where the soil has not been disturbed.
Insect-eating birds are major grasshopper predators, especially in early summer when they must gather high-protein food for their young. While young grasshoppers are feeding in sheltered areas, many are eaten by spiders, ground beetles, frogs and other predators. Wet weather favors the development of several strange grasshopper diseases caused by fungi or other microorganisms.
Many bug-eating birds like to hunt by watching for movement from a perch, so studding your garden with trellises, posts and other upright structures can help birds feed more efficiently.
The surest way to protect plants from hungry grasshoppers is to cover them with a barrier, such as a floating row cover or lightweight cloth. Be sure to hold the covers above plants with hoops or stakes, because grasshoppers are more likely to eat their way inside if leaves are pushing against the fabric. In west Texas and other areas where grasshoppers are especially bad, some gardeners make cones from aluminum screening to keep their plants safe from ’hoppers.
Chickens, ducks, guineas and other fowl eagerly snap up grasshoppers, but they can also damage garden plants. Ideally, you might let grassy pathways in your garden grow up a bit, and then move in a group of birds in a moveable pen. Several readers have reported that turkeys are excellent grasshopper eaters, and they don’t scratch around as much as chickens do, so they do less damage in the garden as they forage.
In some areas of the West and Midwest, grasshoppers are so damaging that biological warfare is worthwhile. A naturally occurring fungus, Nosema locustae, weakens and kills grasshoppers when they eat it. Sold as Nolo Bait and Semaspore, this method can help you reduce grasshopper populations at your place over time, making them much easier to manage. Earthworms and most beneficial insects are not harmed by Nosema locustae, but it is damaging to crickets and mantids (both are closely related to grasshoppers). Crickets are major consumers of weed seeds and mantids eat other bugs, so there is a bit of a trade-off here. But for gardeners who can’t walk through their gardens without being socked in the head by a flying grasshopper, Nosema locustae baits are a good choice.
Grasshoppers would rather live in a tall stand of grass and weeds than in your garden, so you may want to let a hedge of tall grass grow up near your garden’s edge in late summer. If you keep your garden weeded, grasshoppers will naturally gravitate toward the grassy patch.
MOTHER EARTH NEWS readers have described several interesting ways to incorporate chickens into a grasshopper control plan, including a fenced garden with a fenced chicken “moat” around its perimeter, and a series of three small fenced gardens, each with a gate into the chicken yard for easy rotation of pecking services. (Sound cool? Check out our instructions on how to build your own chicken moat.) If grasshoppers are getting worse at your place, you may need chickens more than you think.