Grasshopper invasion on the move near Corning

Louise Wood has lived in Flournoy for more than three years and she has never seen anything like the invasion of grasshoppers that have eaten her fruit trees – in particular her citrus trees, this summer.

“I walk out the door and they are flying around my face, getting in my hair and eyes. It’s just horrible,” she said.

Almond and walnut farm manager DC Felciano watched as the infestation consumed an almond orchard’s crop on property west of Corning and in the same area devoured all the leaves in a walnut orchard.

“The almonds are ruined and the walnuts will get terrible sunburn this summer as they have no leaf cover,” he said.

That same day Felciano hired a pest control helicopter to come out and spray pesticide over what is left of the hundreds of acres in orchards he manages in southern Tehama County.

Take a drive about 10 miles west of Interstate 5 down Corning Road to the Paskenta/Flournoy area and the road is covered in the jumping, flying infestation, which cover windshields and bumpers in leggy, winged carcasses.

There is speculation the hoard could be moving east toward Corning. And Tehama County isn’t the only county in the state to become victims of grasshoppers in the millions.

During a recent Tehama County Board of Supervisors meeting, Assistant Agriculture Commissioner Thomas Moss said the department has been receiving reports of destruction caused by the pests, but has yet to determine the overall outcome. The damage won’t be known until the infestation has abated – and when that will be is yet to be seen.

He said the Tehama County Department of Agriculture is sending out a survey to growers and residents to establish an understanding of the problem.

In addition to the surveys, inspectors from the county and state will be onsite to assess the damages.

According to University of California IPM, grasshoppers have chewing mouthparts that remove large sections of leaves and flowers, sometimes devouring entire plants. Garden damage is usually limited to a few weeks in early summer immediately after range weeds dry up. However, during major outbreaks grasshoppers will feed on almost any green plant, and damage may occur over a considerably longer period.

UC IPM reports the pests usually go unnoticed, but when conditions are favorable, like warm, moist springs, their populations can increase dramatically. In search of more food, adult or nymphal grasshoppers may migrate into nearby areas, with severe outbreaks over an extended period of time.

With the outcome of the infestation still uncertain, Moss said disaster declarations must happen within 60 days of the incident, so his department is quickly trying to keep abreast of the situation daily and relay information to the Farm Bureau Agency.

Management

Grasshoppers are among the most difficult insect pests to manage in the garden. When numbers are low, they can be handpicked and squashed.

However, during years as parts of the state are currently suffering, when huge numbers of grasshoppers are migrating, there is almost nothing residents can do to protect plants once the invasion has reached the garden, orchard or pasture.

UC IPM reports the best strategy in agricultural and rangeland areas during major migrations is to treat the grasshoppers with an insecticide early in the season when they are still young nymphs living in uncultivated areas.

Gardeners can apply a bait containing carbaryl around the borders of their garden before grasshoppers arrive. If a grasshopper trap crop is being grown around the border of the garden, these plants can be baited or sprayed with carbaryl or other products to kill grasshoppers. As of Aug. 1, 2020, pesticides containing the active ingredient carbaryl are restricted use materials in California. A valid pesticide applicator’s license is required for their possession and use. For more information see the California Department of Pesticide Regulation website.

These insecticides have only a few days of residual activity against grasshoppers, and because baits lose their effectiveness after rain or irrigation, they will need to be reapplied if migrations continue.

Once grasshoppers have invaded the garden, insecticides won't be very effective and must be reapplied every few days as long as the invasion continues; read the product label to determine the allowable frequency of applications.

“Carbaryl and other insecticides such as cyfluthrin or other pyrethroids commonly used as sprays for grasshopper control are very toxic to bees, natural enemies of grasshoppers, and aquatic life, although carbaryl in bait form is less hazardous to bees. Reserve the use of insecticides for serious situations where they may provide a significant level of control, ideally as baits around the edge of the garden before grasshoppers invade,” UC IPM reported.