Plan now for grasshoppers

When a fierce spring snowstorm howled through eastern Montana and western North Dakota mid-April, despite the challenges it presented, most farmers and ranchers were grateful for the moisture in an otherwise dry winter/spring. Another hope surfaced: Did this late spring storm finally reduce the grasshopper population?

According to Melinda Sullivan, national operations manager in the U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS), the chance that the storm killed grasshopper is slim.

“Snow cover can protect grasshopper eggs from freezing, although for some species, prolonged exposure to subzero temperatures can kill the young inside the eggs,” Sullivan said. “We won’t know for sure if the weather has reduced 2022 grasshopper populations until we survey during the timeframe when grasshoppers generally hatch, which is early June for the TSLN reader areas.”

Although early bitter cold temperatures without snow in late fall may have killed some grasshoppers, only a very wet spring might potentially kill grasshoppers. Landowners probably don’t want to take that chance; being proactive may be the only way to slow down the onslaught of the ravenous insects.

The key is to get a management plan completed early, although USDA/APHIS Gary Adams told people not to get too excited if you see grasshoppers out in April.

“Those aren’t the right kind of grasshoppers; don’t even think about scouting to determine grasshopper numbers until after Memorial Day,” Adams said during a USDA grasshopper webinar in Sidney. “While ranchers are out on their rangeland this time of year, be on the lookout for small, nymphal grasshoppers. Nymphal grasshoppers are about the size of a grain of rice and are hard to see. On warm days, they are more active, and if you look closely, you may see them moving.”

Adams noted that landowners play a critical part in identifying hot spots of hoppers.

“There are areas of concern in Montana based on last year’s drought and high grasshopper populations,” said Adams. “Areas that received treatments in 2021 should see diminished grasshopper and Mormon cricket populations in 2022. APHIS and its cooperators will conduct surveys in June that will enable us to determine the areas where grasshopper or Mormon cricket population outbreaks may threaten rangeland and potentially move to cropland this season.”

The APHIS 2021 adult grasshopper survey identified a few areas of concern in Wyoming for grasshopper outbreaks in 2022. The APHIS Plant Protection and Quarantine Program (PPQ) experts are discussing potential treatments with landowners and cooperators in Natrona and Big Horn Counties, as well as on adjacent Tribal land. APHIS surveys in 2021 for Mormon crickets indicate the potential for high densities in Washakie and Johnson counties in Wyoming.

“We do not anticipate seeing significant grasshopper outbreaks in North or South Dakota based on 2021 surveys and landowner feedback,” said Sullivan. “Low and moderate populations were recorded with limited economic hot spots. However, western portions of both Dakotas continue to experience moderate to severe drought conditions and the long-term forecast predicts limited rainfall. Under those conditions, even low grasshopper or Mormon cricket populations combined with limited grass availability can result in the need for rangeland management to protect the limited forage.”

Sullivan explained that grasshoppers and Mormon crickets are natural components of the rangeland ecosystem. “Most years, pests such as grasshoppers and Mormon crickets don’t cause issues. In low densities there is usually enough forage for them and for the livestock and wildlife feeding on pastures,” she said. “However, when their populations reach outbreak levels, they cause serious economic losses to agricultural resources. Specifically, for livestock producers, grasshoppers can significantly reduce available forage on rangelands, forcing producers to buy supplemental feed or sell their livestock at reduced prices.”

Crops aren’t immune, either. Sullivan said large grasshopper and Mormon cricket populations can devastate cultivated crops such as alfalfa, wheat, barley, and corn. “On a year with an explosive population of grasshoppers or Mormon crickets, reducing their numbers with suppression treatments improves the amount of life-sustaining grassland forage available for wildlife and livestock.”

Grasshopper outbreaks can cause significant losses to beekeepers, and their colonies can suffer losses as well when grasshoppers destroy bee rangeland food sources. Beekeepers are then forced to move their hives or buy alternative food sources to sustain them.

“They can also experience greatly reduced honey production during these times. Grasshopper outbreaks likely impact wild pollinators similarly by destroying or reducing flowering plants,” Sullivan said. “Damage from grasshoppers and Mormon crickets reduces habitat and food sources for wildlife, which can threaten animal and plant biodiversity as well as the rangeland’s ability to sequester carbon.”

APHIS experts will conduct early season (nymphal) surveys in areas of concern and provide technical assistance for treatments. When funding is available, APHIS shares the costs of providing suppression treatments on rangelands, per Section 7717 of the Plant Protection Act.

During the grasshopper seminar, Adams mentioned that wet, rainy springs can knock back the populations, as the insects become more susceptible to a fungus that causes them to lose eggs and die. They also cautioned that the type of grasshoppers matter and some are not necessarily a risk to range and cropland. (www.idtools.org/id/grasshoppers.)

However, working sooner rather than later with professionals is paramount if you hope to achieve grasshopper control this summer using suppression strategies.

“If it turns out you were wrong and don’t need assistance in grasshopper control, you can always change plans,” said Adams. “However, if you’re in the midst of grasshopper infestation either on your rangeland or in your crop, it’s almost too late to effectively spray.”

Concerned landowners should reach out now to their local State Plant Health Director (https://www.aphis.usda.gov/aphis/ourfocus/planthealth/ppq-program-overview/CT_SPHD) (http://www.aphis.usda.gov/planthealth/sphd), local Extension offices, or their local County Weed and Pest Districts if they are concerned about high densities of grasshoppers on their rangeland.