Clint Perkins

I have seen and have received several phone calls about grasshoppers in the fields over the past several days. It is that time of year to start thinking about treating your hay meadows, pastures and around your houses. Thus far we have seen quite a few grasshoppers, but they are still fairly small. At this stage of their life they are pretty easy to control. Get your sprayers calibrated and prepared for a busy season.

Grasshoppers are occasional pests. The differential grasshopper and the four other species (red legged, migratory, two striped and Packard grasshoppers) cause most of the damage seen by homeowners and hay producers in Texas. Because grasshoppers require relatively large breeding grounds in which to build large populations, most severe outbreaks occur near farmland and other less disturbed areas, such as in rural communities, farmsteads and urban fringe areas. Although grasshopper damage is difficult to completely prevent during outbreak years, producers can minimize their impact.

Grasshopper eggs are generally laid during the fall and late summer in rural, non-crop landscapes. They may also be laid in crop areas after harvest, within weedy fields and in forage areas and pastureland. Eggs usually hatch the following spring, in late May to June. The development of grasshopper nymphs to the adult stage requires 40 to 60 days or more.

Adult forms of the differential grasshopper usually appear in mid June. The adult grasshopper is the most voracious feeder, and is able to disperse over large areas due to its strong wings. The adult grasshopper is the most likely stage to invade and damage pastures and hay fields.  What insecticides can be used on pastures and hayfields?

Always read and follow all label instructions on pesticide use and restrictions. Information below is provided for educational purposes only. Read current label before use. These are just examples of pesticide products that control grasshoppers.

Mustang Maxx (9.6% zeta-cypermethrin): The first pyrethroid insecticide labeled on pastures and hay fields. Applications may be made up to zero days for forage and hay, seven days for straw and seed screenings. Labeled for a large number of insect pests, including armyworms, grasshoppers.

Lambda Cyhalothrin Products: Pasture and rangeland grass, grass grown for hay and silage and grass grown for seed. Pasture and rangeland grass may be used for grazing or cut for forage zero days after application. Do not cut grass to be dried and harvested for hay until seven days after the last application. This product tends to be the most economical.

Baythroid XL: Pasture, rangeleand, grass grown for hay and seed. Zero days to grazing or harvesting hay.

Dimilin 2L: Dimilin is labeled for grasshopper control for pastures, including forage that is mechanically harvested, roadsides, fence rows and other non-crop areas. Wait one day until harvest. Label does not list a restriction on grazing. To be effective, Dimilin must be applied when young hoppers are about one-quarter inch. Dimilin is not effective on adult (winged) grasshoppers. If adults are present, add a second insecticide that is effective on adults. Dimilin must be eaten by the grasshoppers to be effective. This product provides residual control for up to two to three weeks or longer, as long as forage is not removed from the field. Dimilin acts as an insect growth regulator and is less toxic to many non-target organisms relative to those listed above.

Sevin 4F, Sevin XLR, Sevin 80S, Generic Carbaryl: When applied to pastures, there is a 14-day waiting period before grazing or harvesting.

Malathion 57% and Malathion ULV: Zero days to harvest or grazing.

Prevathon, 5% rynaxypyr: Prevathon has a 2ee label for control of grasshoppers in pastures and hay in Texas and Oklahoma. Prevathon has a zero-day waiting period for harvest or grazing and is not a restricted use insecticide.

When should insecticides be applied?

Monitor grasshopper infestations and treat threatening infestations while grasshoppers are still small and before they move into crops and landscapes. Immature grasshoppers (without wings) are more susceptible to insecticides than adults. Applications may be made any time after eggs begin to hatch. For optimum results, applications should be made when the majority of the nymphs have reached the second and third instar stage of development.

You can estimate the size of a grasshopper infestation by surveying for nymphs or adults with the “square foot method.” Count the number of grasshoppers that hop or move within a square foot area. Then take 15 to 20 paces and sample another square foot area. Make 18 samples in all. Then add the numbers from each sample and divide the total by 2 to obtain the number of grasshoppers per square yard. If most grasshoppers you see are first to third instar (wingless and generally less than one-half inch long), divide the number by three to give the adult equivalent. Count fourth instar and older nymphs as adults.

I know right now many folks are gearing up to spray weeds and/or using liquid fertilizer, so it would be very economical to go ahead and also spray for the grasshoppers at the same time. Be sure and follow label directions when using any pesticide. The label is the law when dealing with any pesticide. If you have any further questions, please contact the Smith County Extension Office, 1517 W. Front St. in Tyler, or call 903-590-2980.