While the most important action farmers can take to protect their crops is to be aware of the most current insect monitoring information from provincial ag departments, says Dan Johnson, an environmental science professor at the University of Lethbridge. the best in-field tip remains the same year after year: know the difference between grasshoppers that damage crops and those that do not, and check for them at the right times.
As many as 25 grasshopper species can be found in a single field, and only a few of those species are pests; however, in some years, the pest species are the most numerous ones. As a rule of thumb, Johnson says it’s not a pest if the grasshopper:
- has coloured wings;
- makes any kind of noise, such as clicking when it flies, scritching when it’s sitting, or singing in the ditch;
- flies before the first of June; or,
- sits in a crop and does not damage it. Many grasshoppers will not eat particular species of crops or plants. They’ll live in a field but not eat some kinds of plants, and in some cases certain species will avoid crops.
Consulting a comprehensive guide for grasshopper identification and control such as Grasshopper Identification and Control Methods to Protect Crops and the Environment (find it on numerous websites) will help farmers sort pests, such as the two-striped, Packard’s, lesser migratory and clear-winged grasshoppers, from harmless or beneficial species.
Grasshopper identification by growers is vital for monitoring species shifts, says Johnson, which can change over the course of a year, or from year to year. For example, Alberta producers scouting their fields near Coronation, Consort and Youngstown may have noticed a shift in grasshopper species prior to the devastating outbreak in 2002.
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“For two years before it happened, I could see that a species called the clear-winged grasshopper, which had been extremely uncommon for years, was coming back with a vengeance because of the dry conditions,” says Johnson. “The forecast gave the warning, and it turned out to be right. It was a wipeout. The grasshoppers were so heavy and so hungry a lot of the fields looked like the barest summerfallow ever, yet they weren’t summerfallow — they were crops. The level at which young grasshoppers begin to seriously threaten cereal crops is around 10 to 15 per square metre, but during the drought years they were hatching at hundreds per square metre in some fields.”
Small shifts in populations and the species that dominate are natural, but it’s a whole different ballgame, says Johnson, when a population swings dramatically, especially if growers are used to dealing with certain species and then must adapt quickly to new ones showing up in their fields. “We need to anticipate those shifts and be ready,” he says.
It’s also important for younger generations to become familiar with identifying grasshopper species. “The farmer generations are turning over now. The young farmers are educated, ready to go and hard-working. But they might lack experience because maybe they haven’t lived through outbreaks, or they’ve only seen one and it’s a particular kind of grasshopper,” says Johnson.