Snow, cold puts end to hoppers

The beginning of this year's winter wonderland might be the finish for the little troublesome hopping creatures that have caused a bit of havoc this year in Montana, including Sanders County. They might be small, but they came in big droves and were tough to eradicate and their disappearance is only until spring, according to entomology experts. 

Grasshoppers were especially troublesome this year, primarily due to the warm and dry conditions throughout the state, according to Kevin Wanner, an associate professor of entomology and a cropland extension specialist at Montana State University. And even after chilly days and even light snow a week ago, grasshoppers were present in Sanders County - though not in the numbers of warmer days. The heavy snow that came Friday evening and Saturday, along with the low temperatures, might have taken care of the issue. One problem is grasshoppers lay eggs even late in the year and those eggs winter over for a spring hatching. 

This year they were worst in the eastern portions of Sanders County from Plains to the Flathead Indian Reservation, according to Gary D. Adams, the state plant health director for the Animal and Plant Inspection Service of the U.S. Department of Agriculture in Billings. "There are a few hundred different species of grasshoppers in Montana. However, only about a dozen of those species reach population levels where they might be considered a serious pest," said Adams, adding that the clear-winged and lesser migratory grasshoppers are the most predominant species in Sanders County. "The clear-winged and lesser migratory grasshoppers originate on rangeland, but can migrate to cropland later in the season, impacting both farmers and ranchers," said Adams.

Ruth O'Neill, a research associate with the Department of Plant Sciences & Plant Pathology at MSU, said there are about a dozen species that normally cause the most damage and in a typical year the two-striped grasshopper, the Packard's grasshopper, the migratory grasshopper, all of which are in the melanoplus species, and the Camnula, also known as the band-winged grasshopper, are the worst ones that cause the most damage for crops. The three melanoplus species eat away at a broad variety of crops and broad-leaved plants, she added.  

"On rangeland the grasshopper species assemblage is much more diverse, and includes about a dozen additional common species. I don't know which species were a particular problem across Montana this year. I worked a bit in an alfalfa field in Broadwater County this year and saw a big problem there with the migratory grasshopper," said O'Neill. 

Adams said that grasshoppers and Mormon crickets are natural components of the rangeland ecosystem and don't cause issues most years, however, when their populations reach outbreak levels, they can cause serious damage to agricultural resources. He also noted that Montana has gone through a significant increase of grasshopper populations because of natural environmental factors. "These pests can also cause significant economic losses for livestock producers by significantly reducing available forage on rangelands, forcing producers to buy supplemental feed, find additional pasture, and/or sell their livestock at reduced prices," said Adams. "Additionally, large rangeland grasshopper and Mormon cricket populations can move into and devastate cultivated crops like wheat, barley and hay. The reduction of hay impacts the ability of ranchers to feed their livestock," said Adams, who added that some beekeepers have moved their hives away from areas with large grasshopper populations.

Grasshoppers normally peak in July and August and continue through autumn. However, this year, the critters continued to be reported in places as late as last week just prior to Friday's heavy snow. "I have seen a few around here as well in the past week. The ground is still warm, but as soon as it freezes I am assuming that will be the end of the grasshoppers, except for the handful of species that are adapted to overwinter as juveniles," said O'Neill.

Wanner also said that it's not unusual to find some of the pesky bugs after the first cold weather. He added that snow can also act as an insulation for them. "With insects that are adapted to our climate, the effect of cold depends on two things - how cold and for how long. So, if it's very cold, less time is needed to kill them," he said. Wanner said he'd be surprised to see any after the negative temperatures of last weekend.

The grasshoppers in Montana range in size from the spur-throated grasshopper, which is about 5/8th of an inch, to the red-shanked grasshopper, which can get to over two inches long, according to O'Neill, although she noted there are larger hoppers elsewhere in the United States.

Most grasshoppers overwinter in the egg stage in the soil, according to Laurie Kerzicnik, an urban entomology and an associate extension specialist at MSU. After their eggs hatch in mid- to late spring, the nymphs (immatures) immediately begin feeding, according to Kerzicnik. Wanner said that the warmer autumn this year will bring more female egg laying. He said that a dry spring will mean a greater survival rate for the newly hatched hoppers. On the other hand, a cool wet spring brings with it a higher mortality rate. "Grasshopper populations cycle. They tend to increase during hot and dry conditions," said Wanner, who added that the grasshopper populations have been increasing during the last two years. He said it's not unusual to have high populations in the late fall because they've had a hot, dry summer to grow and they continued to feed, mate and lay eggs into the autumn because it stayed warm. 

He also noted that their population increases will depend partly on the climate over the next few years. "At high populations, grasshoppers are notoriously difficult to control, no easy solutions at high populations. In rangeland, their populations can be suppressed with insecticide applications," said Wanner. He said that in large rangeland areas a "skip pass" technique - alternating the spraying of strips of land - can be effective at suppressing grasshopper populations. "Grasshoppers move enough from the untreated strip that they encounter the treated pass and are exposed to the insecticide," said Wanner. "Grasshoppers typically move into crops from surrounding grassland. If numbers exceed thresholds the edge of the crop can be treated with insecticide as a barrier. Systemic seed treatments can be applied to fall planted crops, planting one or two passes around the edge of the field with the treated seeds," he added.

Kerzicnik said the high grasshopper numbers this year could be because of the abundance of the 2019 yellow sweet clover bumper crop, a plant favored by the two-striped grasshopper, and due to a wet spring last year, when grass was abundant. Adams agreed that the mild winter and hot, dry summer led to the population surge. She said that for the most part the grasshopper populations were not managed, which allowed the numbers to increase. "Once grasshoppers are adults and have entered the yard and garden, management is extremely challenging," she said.

Wanner said grasshoppers have become adapted to cold temperatures. "A hard frost or two, some freezing temperatures, in the fall will kill the adults," he said. The entomology professor also said that 2009 and 2010 in Montana was the last time the grasshopper populations had a significant increase. He believes the grasshoppers have been growing over the last couple of years. And if it's a mild, warm and dry in the spring of 2021 and the summer is hot and dry the grasshopper outbreak will probably be worse. 

Grasshopper and Mormon cricket populations increase and decrease in response to environmental factors, according to Adams, which is what happened this year. "Natural environmental factors will dictate what grasshopper populations will look like state-wide in future years," said Adams. "Extreme cold winters can reduce grasshopper populations and warm, wet summers enhance diseases that also impact grasshopper populations," he added. "Based on historical date and experience," he said, "we expect that the state will see similar populations in 2021."