Grasshoppers cause damage to gardens across the U.S. With about 600 different species in the U.S., grasshoppers are common across the country. About 30 of these species are considered to be garden pests and damaging to plants, thus, the purpose of this article is to answer the often-asked question: How to kill grasshoppers by natural and organic means or with chemicals.
But just a quick note before we talk about grasshopper control -- these insects also can benefit the environment because their excrement provides nutrients to fertilize plants.
The grasshoppers themselves are also food for birds, lizards, spiders, and other arthropods and insects.
Damage from Grasshoppers
But grasshoppers also cause damage. Because they are herbivores, they feed on grasses and the leaves and stems of plants; so when large numbers of certain grasshopper species infest farms or garden areas, they can cause extensive plant damage and loss. In fact, in peak years, grasshopper infestations have been known to destroy or consume entire crop fields.
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 tomatoes leaves. The more grasshoppers there are in any one place, however, the more likely they are to feed on a variety of plants besides the ones they most prefer.
Grasshoppers are most likely to cause damage in sub-humid, semi-arid areas in the middle of the U.S. – from Montana and Minnesota to New Mexico and Texas.
- are reddish brown to olive green, depending on species.
- may be as long as 1-3/4 inches, with narrow bodies.
- have distinctively long, angled back legs, enabling them to be strong jumpers.
- have protruding heads dominated by large eyes and chewing mouthparts.
- have wings and can fly.
Young grasshoppers are smaller than adults and are wingless. When first hatched, these nymphs will be white. As they grow, they will take on the color of the adults of their species, and wings begin to appear as small pads.
Grasshoppers will start being seen in early spring, with the greatest numbers generally occurring in mid-summer. In addition, grasshoppers populations are likely to be highest when the weather is hot and dry.
Natural and Organic Control 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:
- Till the ground in mid- to late summer to eliminate areas in which females would lay their eggs – which overwinter under the soil and hatch in the spring.
- Till the ground in late fall and/or early spring to destroy eggs that were laid the previous summer.
- Get rid of weeds even in areas that don't have plants to reduce the availability of food for newly hatched nymphs.
- For natural animal control, encourage grasshopper predators such as birds in and around garden areas.
- Cover grasshopper-preferred plants with cheesecloth to protect them.
Chemical Control of Grasshoppers
When necessary, chemical bait and spray pesticides that are labeled for grasshopper control can also be used, reading and following all label directions. According to Colorado State University Extension, 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.
So when these 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.
The university also notes that adding canola oil to an insecticide spray can improve control by making the treated plants more attractive to the grasshoppers.
For a list of approved insecticides and general control, visit the university's page on Grasshopper Control.