Before undertaking wholesale eradication, though, be aware that grasshoppers do offer some benefit to the environment. The grasshoppers themselves serve as food for birds, lizards, spiders, and other arthropods and insects, and their excrement provides nutrients to fertilize plants. A handful of grasshoppers in your garden is no cause for alarm and may actually be a sign of helpful diversity. It’s not until the plant damage becomes widespread that serious control efforts should be considered.
Identifying Grasshopper Plant Damage
Grasshoppers are herbivores that feed on grasses and the leaves and stems of plants. The symptom of grasshopper damage is much the same as for other gnawing insects: ragged and chewed holes in the leaves, stems, and fruit of plants. Although grasshoppers will feed on many different plants, they often prefer (and cause the most damage to) small grains, corn, alfalfa, soybeans, cotton, rice, clover, grasses, and tobacco. They may also eat lettuce, carrots, beans, sweet corn, and onions. Grasshoppers are less likely to feed on plants such as squash, peas, and tomato leaves. The more grasshoppers that are present, the more likely they are to feed on plant species outside the preferred group. Grasshoppers are most likely to cause damage in the central U.S.—from Montana and Minnesota to New Mexico and Texas.
Identifying Grasshoppers
Young grasshoppers are smaller than adults and are wingless. When first hatched, these nymphs are white. As they grow, they will take on the color of adults of their species, and wings begin to appear as small pads. Adult grasshoppers are reddish-brown to olive green, depending on the species. They have narrow bodies and can be as long as 3 inches, though most are 1 3/4 or less. Most grasshoppers have distinctively long, angled back legs that allow them to be strong jumpers. They have protruding heads dominated by large eyes and chewing mouthparts. Adult grasshoppers have wings and can fly. Grasshoppers first appear in early spring, with the greatest numbers generally occurring in mid-summer. Grasshoppers’ populations are likely to be highest when the weather is hot and dry. Grasshoppers are hemimetabolous insects, which means they do not undergo metamorphosis, as do butterflies and many other insects. Instead, they hatch from eggs into nymphs (“hoppers”) that undergo five molts, gradually taking on the adult appearance and size. When population densities become very high, environmental conditions may cause some species to change color and form swarms. At this point, they are often known as locusts.
9 Ways to Get Rid of Grasshoppers
Because grasshoppers are very mobile, they are also very difficult to control. The best way to control grasshopper damage is to prevent the growth of populations. A number of natural solutions can be used and should be tried before you reach for synthetic chemical controls.
Encourage Natural Predators
Many insect-eating birds, such as swallows, are notable grasshopper predators. Other animal species also eat grasshoppers, such as praying mantis insects, small snakes, and toads. Any garden practices that encourage these natural predators will be effective at reducing or eliminating grasshopper infestations.
Till the Ground
Till the garden soil from mid- to late summer to eliminate areas where females lay their eggs. These eggs overwinter in the soil and hatch in the spring. Till the ground again in late fall and early spring to destroy the eggs that were laid the previous summer.
Eliminate Weeds
Eliminate weeds even in areas that don’t have garden plants to reduce the availability of food for newly hatched nymphs. Good weeding practice goes a long way toward reducing overall grasshopper populations.
Cover Vulnerable Plants
Cover vulnerable plants with cheesecloth or crop covers to protect them from feeding by grasshoppers. This method will protect plants from arriving insects, but it may need to be used in conjunction with other methods aimed at eliminating grasshoppers that are already present.
Apply Garlic Spray
Blend two cups of garlic with 10 cups of water, boil the mixture, and let it sit overnight. Then, mix one part of this solution with 3 parts water in a spray bottle and moisten the leaves of vulnerable plants with the spray. This spray will deter grasshoppers and other feeding insects.
Apply Flour to Plants
Dusting plant leaves with flour will gum up the mouths of grasshoppers as they feed. This remedy will need to be reapplied whenever rain washes away the flour.
Keep Chickens
Chickens can eat vast quantities of grasshoppers, so if your community and circumstances allow it, two or three chickens roaming your garden can provide near full control grasshoppers and other insects. Other domestic birds, such as ducks and geese, also serve this function.
Apply Biological Controls
Among the preventive measures that work for grasshoppers are Nosema locustae and Beauveria bassiana, fungi that affect the digestion of grasshoppers; azadirachtin, a natural biological agent that is found in neem oil; and organic pyrethrins. If organic control is your goal, avoid compounds labeled as pyrethroids. These pesticides add synthetic chemical compounds to natural pyrethrins, and thus cannot be considered organic pesticides.
Use Chemical Pesticides
When necessary, chemical bait and spray pesticides that are labeled for grasshopper control can also be used, reading and following all label directions. However, baits and sprays need to be applied to developing stages of grasshoppers and concentrated at sites where egg-laying occurs, as the ability to control grasshoppers declines as they develop and migrate. Carbaryl is the most effective chemical pesticide on grasshoppers, but unfortunately, this chemical is also highly toxic to beneficial insects. Baits containing carbaryl are safer than sprays when it comes to protecting bees and other beneficial insects, but even baits should be used very carefully and only in areas where you know grasshoppers are feeding. When chemical treatments are used to kill grasshoppers, they should be focused on young grasshoppers and breeding sites during spring and early summer, depending on the geographic area. Adding canola oil to an insecticide spray can improve control by making the treated plants more attractive to the grasshoppers.
What Causes Grasshoppers in the Garden?
Grasshoppers are likely to be a problem in your garden whenever regional populations have spiked. Your garden is especially prone to damage if you are growing favorite foods, such as corn, lettuce, and beans. But during peak years, grasshoppers will eat almost any garden crops as well as ornamental plants. In peak years, grasshopper infestations have been known to destroy or consume entire crop fields. In some areas, up to 25 percent of crops are routinely lost to grasshoppers.
How to Prevent Grasshoppers in the Garden
Preventing grasshoppers during years when regional populations are high requires multiple strategies since virtually no garden will be immune. For the years that grasshoppers are most prevalent, you can avoid growing the plant species favored by grasshoppers, while at the same time encouraging natural predators and employing other weed control methods and organic repellants. But the reality is that it’s very difficult to prevent grasshoppers entirely during those years when regional infestations are high.
Grasshoppers vs. Beetles
Many species of beetles including the notorious Japanese beetle also eat plant foliage, so identifying the guilty insects can sometimes be tricky. However, grasshoppers typically produce a distinctive type of plant damage, eating away large portions of leaves. The holes are generally large with ragged edges. And grasshoppers usually begin their infestation of plants in the spring, while the insects are still young. Beetles usually begin the feeding assault later in the summer, after they have evolved into adults from the larval grub phase. Beetles will devour nearly the entire leaf but they usually leave behind a wispy skeleton of leaf veins. They can nearly defoliate an entire plant, while grasshoppers are more random feeders. Beetles will often remain boldly feeding on the plant as you observe them, while grasshoppers are more cautious, usually jumping or flying away when you approach. Long Zhang, Michel Lecoq, Alexandre Latchininsky, David Hunter Annual Review of Entomology 2019 64:1, 15-34
