Grasshoppers have been a crop pest since the beginning of time, they are even mentioned in the Bible as the Plague of Locusts. "Stretch out your hand over Egypt so that locusts will swarm over the land and devour everything growing in the fields, everything left by the hail .... By morning the wind had brought the locusts.." ... Exodus 10;12 - 13
Grasshoppers can be a serious pest in the garden depending primarily on environmental variations.
Grasshopper Populations surge when environmental factors allow excessive amounts of hatchlings to survive.
A wet cool spring, with temperatures below 65 degrees, results in less eggs hatching. A warm, dry spring will result in more grasshoppers in the fall and makes grasshopper control a necessity for gardeners.
Grasshoppers, being extremely mobile are difficult to control. Grasshopper eggs begin hatching in late Spring and early summer. The grasshopper nymphs feed on tender grass and succulent plants near where they hatched. As Grasshoppers develop they spread to adjacent areas and feed on an increasingly-diverse variety of plants. They devour almost any type of foliage, but generally prefer softer vegetation such as lettuce, rather than tougher material, such as tree leaves. As far as vegetables go, they prefer leafy vegetables - lettuce, carrots, onions. They usually avoid squash, peas and tomato leaves. They do, however, like tomato fruit.
If grasshopper control is a major problem, besides planting the softer vegetables that grasshoppers prefer, a good strategy is to plant early-maturing varieties of other crops that you can harvest before mid -to -late August.
Grasshopper nymphs live for up to 2 months, after which the adults appear and continue feeding until they are killed off by cold weather.
While adults are busy reproducing and laying eggs, nymphs have only one focus... To Chow down on your Lawn and Garden. Damage caused by grasshoppers appears as irregular holes at the edges of leaves.
Horehound, Cilantro, and Calendula are herbs that repel grasshoppers. Planting a border of these plants , or having them scattered around the garden area will help keep grasshoppers at bay. Garlic not only repels vampires and the opposite sex but it also repels grasshoppers - Garlic Oil also serves as a deterrent of grasshoppers as well as other Garden pests - it must continuously be reapplied.
Some insects commonly feed on grasshoppers. Blister beetles feed on grasshopper eggs - but you really wouldn't want them around just for the sake of grasshopper control as they also bite animals and humans leaving nasty little blisters.
Many birds feed on grasshoppers. - But birds will also feed on many of your ripe garden crops . You will have to judge whether using birds in a grasshopper control scheme is actually advantageous. If you believe it would be then consider that many birds hunt by watching for movement from a comfortable perch, if your not concerned with birds also eating your crops you could put multiple perches such as trellises, posts and other upright structures to attract birds who will assist in grasshopper control as well as controlling other garden pests.
Adult robber flies are common predators of grasshoppers during summer . Composite flowers such as dandelion, chrysanthemum, yarrow, sunflower, dahlia and zinnia attract robber flies as well as predatory wasps and other beneficial insects including pollinators. I generally have sunflowers scattered randomly in advantageous spots, not just for grasshopper control but they have other benefits as well.
Praying Mantids are an adored beneficial insect and a general predator of most pest insects including grasshoppers.
Young grasshoppers prefer sheltered spots of dense vegetation, it is here that they fall prey to spiders, toads, ground beetles, and other predators. Patches of dense mixed grasses and flowers can serve as early-season traps for young grasshoppers.
Chemical Control - Baits and Sprays
Sprays and or baits are a successful grasshopper control only if properly used, they must be applied to developing stages of grasshoppers and concentrated at egg laying sites . Ability to control grasshoppers declines as the grasshoppers mature and scatter.
The most effective grasshopper controls are baits that contain Nosema locustae a single-celled protozoan that infects and kills most species of grasshoppers, locusts, and some crickets. It is non-toxic to humans, and animals. Nosema locustae is sold under the trade names of NOLO Bait or Semaspore. Only young grasshoppers are susceptible, and it is ineffective as a grasshopper control after adult migrations have occurred. It is also fairly slow acting and does not equally infect all grasshopper species. It may also effect some varieties of Praying Mantis.
Baits containing Sevin are also useful. Bait formulations are made by mixing the insecticide with a grain favored by the grasshoppers, it kills off any that feed on it. Sevin baits become ineffective after a rainfall and must be reapplied.