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Should gardeners be worried about grasshopper invasion?

KENNEWICK -- The news about a prospective onslaught of crop-devouring grasshoppers this summer had home gardeners in a tizzy last week.

What would happen to lovingly tended gardens and landscapes?

What could be done to stop the anticipated invasion of hungry insects?

I decided to go right to the source, Washington State University entomologist, Richard Zack, who had been quoted in the WSU News Service story.

Zack says the expected large population of grasshoppers shouldn't be a problem for the general public with small gardens.

Areas of concern are open range and pasture lands. One of the worst major grasshopper outbreaks in the western US during the last century occurred in 1985 and resulted in the federal government treating more than 13 million acres of land. In Washington, the most recent bad grasshopper outbreak was in 1978 and 1979.

Last year in Oregon, where grasshopper populations are monitored in rangeland, the areas closest to us with economic levels of grasshopper adults were Umatilla, Union, Morrow and Wallowa counties.

Because of the success of treatments applied in 2008 and in 2009 to grasshopper "hot spots" in Oregon, the Oregon Department of Agriculture anticipates a declining threat there this year.

So why the dire warnings about the worst grasshopper outbreak in 30 years?

Zack and other entomologists have put the warning out regarding the grass-hoppers because it brings attention to the potential problem. This is important so that funds can be allocated to manage the pest before it has a serious economic impact on agriculture in Western states, such as Washington and Oregon.

Grasshopper outbreaks are cyclical, building and declining over time. Because the grass-hopper population has been significantly large over the past several years, and because our warm fall and mild winter weather is favorable to the grasshopper population, state and federal agencies responsible for keeping grasshopper populations in check are letting the public know about this potential threat.

Most area home gardeners within city areas won't have a significant problem with grasshoppers. However, homeowners and farmers next to open sagebrush or rangeland may be bothered by the predicted grasshopper attack.

Unfortunately, there's not much that one gardener or farmer can do to effectively control these ravenous "hoppers."

On federally and privately owned rangelands, baits toxic to grasshoppers are spread in affected areas or "hot spots" when the grasshoppers are young and immature.

There's not much we can do in our gardens if swarms of mature adults arrive to dine.

If it gets bad, Mike Bush, WSU Extension educator and entomologist in Yakima County, says home garden insecticides won't really do the job. He recommends using insect nets to trap the hoppers, using a shop-vac to suck them up or even starting a grasshopper collecting competition between the children in your family. He also notes that chickens and gulls like eating grasshoppers.

That's the bad news.

The good news is that early May has been colder and wetter than normal. Warm, dry early May weather favors the maximum survival rate of young grasshopper nymphs, but cold, wet weather increases mortality.

So while our gardens have had a slow start, the weather also may have meant that the worst grasshopper outbreak in 30 years won't happen this year. We'll see.

* Marianne C. Ophardt is a horticulturist for the Washington State University Benton County Extension Office.

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