Areas see grasshopper increase

SANDERS COUNTY – Although grasshopper populations have seen a significant decrease in much of Montana, some areas in Sanders County have experienced a boom in numbers this year.

According to the U.S. Department of Agriculture’s State Plant Health Director, Gary D. Adams, recent surveys of the county have shown some areas have high grasshopper activity.

 “Each summer from mid-July through mid-August, the USDA conducts surveys for adult rangeland grasshoppers,” Adams explained. “We generally surveyed Sanders County the week of July 21 and I can confirm that several areas of the county showed relatively high densities.”

The Animal and Plant Health Inspection Service conducts the population surveys in 17 western states, including Montana.

The numbers are used to gauge expectations for the following year’s grasshopper populations. Numerous accounts throughout the county have credited grasshoppers for devouring gardens and crops, something that typically occurs when the grasshopper population reaches large quantities.

“Grasshoppers, when at high populations, can consume a significant amount of vegetation,” Adams stated. “Those who rely on rangeland for forage production for livestock can see a significant reduction of available forage.”

If the forage is reduced in significant numbers, Adams said that requires a purchase of more feed for the winter months, affecting the ranchers and farmers experiencing issues. The potential damage can be seen in other areas as well, affecting individual’s gardens as well as cropland that is adjacent to rangeland.

“A few species can migrate from rangeland onto adjacent cropland causing damage,” Adams explained.

When grasshoppers feed, they damage vegetation and grasses by consuming plant stems and leaves. Their feeding habits cause damage to both the plant’s growth and seed production.

Soil degradation and erosion, disturbance of nutrient cycles, interferences with water filtration, and possibly permanent changes in the vegetation and wildlife of the rangeland ecosystem are also listed by the USDA as potential problems.

In times of drought, grasshopper populations have been known to increase, often times causing “serious losses to rangeland forage,” stated Adams. After a stint of hot, dry weather within the county, grasshoppers have experienced perfect hatching conditions.

The warmer weather also keeps the insects alive, as grasshoppers experience a high mortality rate if conditions are cool and wet.

“The primary factor that decreases grasshopper populations is natural pathogens in their population, which often occur when rainfalls occur at the right time to keep humidity up to encourage growth of the fungi that kill grasshoppers,” Adams explained. “Extended dry seasons, drought, often result in an increase in grasshopper populations.”

After a lull in grasshopper numbers, high populations hit a peak within Sanders County in 2010, following a few years where numbers were down. Back in 2003, the county showed a significant increase in grasshoppers as well.

Numbers may be on the rise again. Once grasshoppers reach an adult stage, pesticides are often the only way to decrease numbers. Adams stated that this late in the game, the best plan of action may be to be proactive next year. He said early monitoring in the spring to find hatching beds, otherwise known as egg beds, is an effective way to help control population numbers in smaller areas.

Grasshopper bait is commonly used to rid the insects in their hatching beds.

Although it may be late this year to combat high numbers, Adams said the USDA is always there to help.

“The USDA can sponsor public outreach meetings on grasshopper biology and management options,” Adams stated. “These can occur during the winter to allow us to prepare for next year’s potential for continued high populations.”

Those interested in setting up classes should contact a Sanders County Extension Agent at 827-6934.