Vegetable IPM Advisory • Veg 2025

Grasshoppers – Agricultural Sites

April 30, 2025
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agricultural grasshoppers

Is the Grasshopper Forecast Grim This Year?

All we can say with certainty is that there are thousands upon thousands of grasshopper eggs in northern Utah’s soil, ready to hatch into tiny, rice-sized nymphs in about three weeks.

But many of these eggs may have been killed over the winter and won’t hatch, or the newly-hatched nymphs won’t survive. And if we have a cool, wet spring, a majority of nymphs will die.

In short, the grasshopper population will be grim in 2025 if the period when eggs hatch is warm and dry.

When do Grasshopper Eggs Hatch?

There are about 70 species of grasshoppers in Utah, and four of them cause the most economic damage. The problem is that they do not all hatch at the same time. Along the Wasatch Front, the earliest hatches in mid-May and the latest in late June.

  • For each species, eggs hatch over a 3 to 4 week period
  • The time from newly-hatched nymph to adult takes 4 to 7 weeks
  • Adults may live several weeks

Two-striped Grasshopper

  • When to treat nymphs: Between mid-May and mid-June
  • Earliest time adults are seen (too late to treat): mid-July
two-striped grasshopper
Two-striped grasshopper nymphs (left) are bright green with two yellow-tan stripes down their backs. Adults (right) may reach 2 inches long. Their body is yellow-tan in color with thick black racing stripes down their backs, coming together at the forewings to form a triangle.

Two-striped grasshoppers are one of the earliest hatching-species in spring and can form dense populations. This is a major pest and very common in small grains, alfalfa, and corn. They prefer tall, lush, broad-leaved vegetation.

Migratory Grasshopper

  • When to treat nymphs: Between mid-May to early June
  • Earliest time adults are seen (too late to treat): mid-July
migratory grasshopper
Migratory grasshopper nymphs (left) are mottled brown-green with black areas, and have black stripes margined with yellow. Adults (right) have a reddish-brown body and are the smallest of the four, at 1-inch long. On the inside and outside of the upper leg (femur), the black is interrupted (in bands).

Migratory grasshoppers are also early-hatching, and feed on both grasses and broad-leaved plants. This species causes more crop damage than any other species in the U.S. Dense populations can destroy small grains, alfalfa, clover, corn, vegetables, and ornamentals. One of the more common species in western Utah.

Differential Grasshopper

  • When to treat nymphs: June
  • Earliest time adults are seen (too late to treat): mid- to late July
differential grasshopper
Differential grasshopper nymphs (left) are yellowish-brown with black chevrons on their femurs. The adult (right) is the 6th largest grasshopper in the world at over 2 inches long. It is brownish-yellow or darker, with black chevrons on the femurs.

Differential grasshoppers hatch in mid to late spring and adults can be found into October. This species is one of the most common in Utah, and often found with two-striped grasshoppers, as they both have a broad host range for feeding, including grasses, weeds, vegetable crops, and fruits. Differential grasshoppers often feed in swarms, causing severe damage. Adults can fly 100 miles at an altitude of 1,400 feet.

Red-legged Grasshopper

  • When to treat nymphs: late June
  • Earliest time adults are seen (too late to treat): early August
red-legged grasshopper
Red-legged grasshopper nymphs (left) are mottled brown to green with black markings. Adults (right) are about 1.5 inches long and brown in color. They are so-named because the hind tibia (lower legs) are red in color.

Red-legged grasshoppers are the last to hatch, but are not as commonly seen. This species is widely distributed in the U.S. but prefers tall vegetation in grasslands, meadows, borders, and roadsides.

Conditions for Survival

Populations of grasshoppers in Utah are cyclical, where they are high over a 7 to 10 year period, then low for a few years. This cycle is regulated slightly by predators and available food sources, and mostly by weather conditions. The main factors are how well eggs can survive the winter and how well nymphs survive right after hatching.

Optimal

  • Winter air temperatures have no effect on egg survival.
  • Consistent snow cover contributes to survival of eggs. The soil will have a consistent temperature and moisture level, and the snow offers protection from predators.
  • Warm and dry spring conditions allow for early and successful egg hatch.
  • High temperatures and adequate rainfall in summer and fall help with early maturity of grasshoppers, provides a long egg-laying period, and results in a good supply of food.

Poor

  • If winter soils are dry and uncovered, eggs may desiccate or die from predation.
  • If spring temperatures are cool, nymphs are not able to move or find food.
  • If plenty of rainstorms occur in spring, newly-hatched nymphs will drown or become embedded in the soil.
  • If the summer is dry, nymphs and adults starve due to lack of food and females have low egg-production.

Management

Natural Predators

These include preying mantids, wasps, spiders, snakes, small raptors (kestrel), some rodents, and specialized nematodes. Managed predators include chickens and Guinea hens. Guineas are known to be highly effective at feeding on grasshoppers and other insects.

Grasshopper Diseases

grasshopper summit disease
Summit disease of grasshoppers is caused by a fungus that “forces” the grasshopper to climb high and grasp the vegetation before it dies.

Diseases are caused by several naturally-occurring fungi, bacteria, and viruses. More than 750 insect-feeding fungi have been documented, with three pathogens occurring in Utah: Beauveria bassiana, Metarhizium anisopliae, and Entomophaga grylii. E. grylii causes summit disease which in optimal years (cool, wet conditions), can cause late-season, widespread mortality of adults. The fungus causes the grasshopper to climb to the top of its plant host, grab the stem with its legs, and slowly die. Fungal spores will then disperse from the grasshopper carcass to infect additional adults.

Cultural Practices

  • Before adults start laying eggs (mid July to early August), try to prevent as much bare soil as possible (by using mulch of any type). Females need bare soil to lay eggs and this will prevent some egg-laying.
  • Since eggs are laid about 1 to 2 inches below soil surface, tilling in fall after the first frost will expose and kill egg pods.
  • A border of grains (wheat, triticale, rye) or rows of grains between crops can attract grasshoppers to these areas. Focus treatment on the grains, which reduces amount of pesticide to the cash crop.
grasshopper trap crop
One option to fight grasshoppers is to plant rows of grains to keep grasshoppers away from the target crop.

Insecticides

Insecticides should target nymphs (see info above on individual species for timing). For optimal results, work with your neighboring farms or rangeland areas to treat as large an area as possible.

Organic options are few and far between, so focus on the above non-chemical options first.

Azadirachtin is derived from the same source as neem oil. This ingredient is an insect growth regulator, and prevents nymphs from molting to the next growth stage. Spray on plants (both foliage and stems). Options are Atrevia, AzaGuard, Azatin O, Azera, and Neemix. Check the label for the site.

Pyrethrin is a broad-spectrum insecticide that kills on contact, and provides 3 to 5 days of residual protection. There are many products with this ingredient, so ask your local pesticide supplier.

Conventional products include more options.

EcoBran is a bait formulated with wheat bran plus carbaryl that is specifically made for grasshoppers. It is sold in 2 lb and 40 lb sizes and there are some local suppliers in Utah so check around first before ordering online. It is sprinkled on the plants and ground.

Other granular baits include Bifen L/P Insecticide Granules and InTice Perimeter Bait.

Sprays include the following:

  • Dimilin is a restricted-use product that is highly effective on grasshoppers as it prevents molting. Use in non-crop areas only such as borders and ditches.
  • Prevathon can be used in pasture, rangelands, corn, alfalfa, and other grass forage crops.
  • Carbaryl has many products and uses.
  • Orthene should only be used on non-edible plants.

Cost-Share Programs

There are no cost-share programs available for residential sites.

Utah Department of Agriculture and Food (UDAF)

  • The UDAF program is available for private agricultural lands only. In Utah in 2024, roughly 400 bags of bait were allocated to treat 10,000 acres and reimbursement was provided to treat 20,000 acres.
  • Landowners may be reimbursed 100% of the cost of the chemical only (not labor or costs for application) or receive free bags of bait (usually on sites less than 150 acres). All applications (labor or hiring an applicator) are organized and paid for by the producer.
  • Before contacting UDAF, it is encouraged for landowners to discuss treatments with neighboring landowners (i.e., a community) so that a large area is treated. However, keep in mind that each individual agricultural landowner within that “community” may need to work with UDAF for individual contracts.
  • Reach out to UDAF for treatment or bait bag(s) – Kris Watson, Program Manager, kwatson@utah.gov, 801-330-8285 (ideally Monday – Thursday).
  • UDAF will follow up to determine whether to make a site visit. If yes, UDAF will determine the grasshopper density and whether treatment is warranted. Often this means the site must have economically threatening grasshopper population which is 8 insects per sq. yd. or greater.
  • Paperwork must be approved by UDAF.

USDA Grasshopper Program

  • This program is overseen by the USDA-APHIS PPQ cost-share program. It works on a first-come, first-serve basis (within the western U.S.), but may require a longer wait than working with UDAF.
  • The program applies to rangeland only, on private, state, Tribal, or Federal lands.
  • There is a minimum acreage requirement of 10,000 acres.
  • The program covers the following: for private lands, 33% of costs from USDA-APHIS and 33% from UDAF; on state lands, 50% of USDA-APHIS and 50% UDAF, and on Federal and Tribal lands, 100% USDA-APHIS.  Any cost share treatments need to be identified well in advance of treatment with additional requirements (letters of request, signed/approved Reimbursable Agreements, etc.).
  • Submit a written request to:  Peter Rockermann, Utah/Nevada State Plant Health Director (peter.rockermann@usda.gov; (775) 484-0762) at 8775 Technology Way, Reno, NV 89521. Or, contact Greg Abbott, Plant Health Safeguarding Specialist, gregory.c.abbott@usda.gov, (435) 896-3842
  • USDA may visit the land to determine grasshopper density, species, life stage and make a decision on whether to treat.
  • USDA will determine the treatment option (carbaryl or diflubenzuron).