Description
Grasshoppers belong to the order Orthoptera and are closely related to katydids and crickets. These highly mobile pests feed on a wide variety of crops and are difficult to control. They can cause serious damage during population outbreaks which increase in early summer and can persist until hard frosts.
Target Crops
Some grasshoppers feed on grasses while others prefer broadleaf plants, including garden and landscape plants. Lettuce, carrots, beans, corn and onions are favored by grasshoppers. Squash, peas and tomatoes are generally not preferred.
Life Cycle
Grasshoppers go through simple metamorphosis with one generation per year. In the fall grasshoppers lay their eggs in the soil in sticky clusters. Dry and undisturbed soil is preferred as opposed to soil that has been tilled or irrigated. The eggs will overwinter and hatch in the spring when soil temperatures reach 50°F for many species. The first nymphal stage is quite vulnerable. If weather is harsh or nymphs cannot find food, many can die. The nymphs continue to molt through 5-6 stages until they reach the adult stage, moving into gardens and fields. These can live for several months feeding on a wide range of crops.
Insecticide Options
These are best applied during the developmental stage of grasshoppers and concentrated at sites where eggs are laid, usually May to June. Where grasshoppers impact several properties, coordinated area-wide control is very useful
Mycoinsecticides that contain entomopathogenic fungus are effective. These include Botanigard, Botanigard MAXX (with Pyrethrin), NoFly, Bioceres and Velifer.
Azadiractin acts as insect growth regulator, antifeedant and ovipositional deterrent. These include Azaguard, Azatin-O, and Molt-X. These can be tank mixed with Beauveria bassiana products for greater efficacy.
Oils and soaps can be effective. Circadian Sunrise is a corn/peppermint oil that suffocates insects. M-Pede insecticidal soap, PureCrop and Suffoil-X are more options.
Protection Plus is a citric acid based product that is oil free, for broad spectrum pest control.
Pyganic, with botanically derived Pyrethrins, is a broad-spectrum organic pesticide, good for a quick knock down.
Garlic or pepper sprays may repel insects off the crops.
Traps
Traps can serve as a quick way to bring down the number of grasshoppers, especially in a home garden or smaller farm. Set up a clear pane of glass vertically among the crops with a container of soapy water below it. The grasshoppers will fly into the glass, fall into the water and die. Another homemade trap is made by cutting the top off a 1-liter soda bottle and reinserting the top, upside down. Add grass or plants to the bottom of the bottle and the grasshoppers will crawl in through the opening but not be able to exit. (NW Center for Alternatives to Pesticides).
A similar method, also ideal for small grasshopper populations is to fill a small dish or can with 1 part molasses and 10 parts water. The grasshoppers are attracted to the molasses and will drown in the solution. Replace the mixture daily for a week to ensure all the grasshoppers are killed.
Baits
Studies have found that mixing canola oil, wheat bran and Beauveria bassiana works as a bait for grasshoppers. The wheat bran protects the entomopathogenic fungus from radiation and UV and the canola oil allows the fungus to stay hydrated for more time, allowing it to stay active for longer periods.
Cultural Control Tips
- Create habitat for birds. More than 200 species of birds prey on grasshoppers as they have a high energy value. Some of the larger species such as kestrels, gulls meadowlarks and Swainson's hawk capture more than 100 grasshoppers per day.
- Ground beetles, such as blister beetles, feed on grasshopper eggs. Building Beetle Banks can encourage these natural predators. Robber flies are also predators of grasshoppers.
- Roto-till or cultivate soil in the spring to destroy overwintering eggs.
- Use floating row covers to protect small garden areas and row crops. Use exclusion netting at entrances to tunnel or hoop houses.
- Mow a 'clean' strip between grassy fields and garden areas to help slow grasshopper migration. Pests are reluctant to enter the strip because it has less food and they are exposed to predators. The wider the better.
- An area with a grasshopper problem one year will probably have an infestation the next year, so don't let pests get out of hand.
- Plant aromatic herbs and flowers like basil, sage, rosemary, lavender, marigolds and calendula to repel grasshoppers. Other repellant plants are sage, juniper, artemisia, forsythia and crepe myrtle. Alternatively, grow sunflowers as a trap crop.
Grasshopper Control in Gardens and Small Acreages - Colorado State Extension
Grasshoppers - Utah State University Extension Fact Sheet
Birds and Wildlife as Grasshopper Predators - USDA
6 Natural Strategies for Managing Grasshoppers, NWCAP
Application of Beauveria bassiana using different baits for the control of grasshoppers
Raising Brix to Beat the Bugs, An Organic Strategy for Grasshopper Control - SARE