There are two keys to success in combating grasshopper infestations in the yard and garden: 1) work together as a neighborhood to treat as broad of an area as possible as soon as grasshoppers begin to move into yards from nearby open fields and rangelands, and 2) initiate control while grasshoppers are young. When grasshoppers become adults, they eat much more per day and can fly over treated areas.
Grasshoppers lay their eggs in undisturbed soil in the late summer and fall. Eggs hatch the following spring and the nymphs (young grasshoppers) walk until they find attractive vegetation to feed on. Grasses and forbs growing on open lands can satisfy their hunger early in the season, but as populations increase in size and non-irrigated plants dry with warming temperatures and reduced rainfall, the grasshoppers will move to where they can find lush, green plants to eat. This is when they become a pest in the landscape and garden. Consider these tips for control.
• Mechanical and chemical methods can be used to control grasshoppers. Mowing a wide swath around borders of open fields can reduce migration of grasshopper nymphs walking across the mowed boundary. Insecticides should also be applied to boundaries between home yards and open fields, hedgerows, roadsides, drainage ditches and other weedy and unmanaged lands. In order to be effective, mowing and insecticide treatments should be initiated while grasshopper nymphs are small and before their developing wing pads are noticeable.
• There are three types of insecticide formulations that can be used for killing grasshoppers: baits, dusts and sprays. Baits consist of wheat bran combined with the insecticide, carbaryl, or a natural grasshopper pathogen, Nosema locustae. Baits should be spread evenly throughout the boundary habitat and grasshoppers will consume the bait as they forage. Baits selectively kill only grasshoppers and other foraging insects. They must be reapplied following rainfall or sprinkler irrigation. Examples of carbaryl bait brands include Lily Miller Grasshopper Bait, Sevin 5 Bait and Eco Bran 2 percent. Baits containing the natural pathogen include NOLO Bait Biological and Planet Natural Semaspore Bait.
• Carbaryl (Sevin) is the only type of dust registered for home yard application. Dusts are easy to apply, but are more expensive than sprays and must be reapplied after rain or irrigation. A number of insecticide sprays that can suppress grasshoppers include malathion, permethrin (Spectracide, Bonide Eight, Basic Solutions), bifenthrin (Allectus, Brigade, Sniper and Talstar) and carbaryl (Sevin). Some spray products are not for use on edible plants and some are restricted to licensed applicators only, so be sure to read the product label before purchase and application. Sprayable formulations tend to be less expensive and can kill on contact and when grasshoppers eat the treated vegetation. Sprays are not selective and can kill beneficial insects, pollinators and other susceptible animals, so careful application and appropriate timing are important to protect non-target animals.
• USDA APHIS offers assistance for grasshopper control on public lands. When grasshoppers occur in high densities, landowners may work together to receive state and federal aid to plan and conduct a cooperative management program. Contact your local Utah State University Extension or Utah Department of Agriculture and Food office for assistance with grasshopper management. For more information, see Utah Pests Fact Sheet: Grasshoppers, ENT 125-08 at http://utahpests.usu.edu.
By: Diane Alston - Jul. 16, 2009