CORONATION, Alta. – In the summer of 2002, major highways were closed in east-central Alberta when driving became too hazardous as clouds of grasshoppers darkened the sky and dead insects made roads too slippery.
This year could be equally bad, say hopper watchers.
“Until we get cold, wet conditions at the right time so they either stop hatching or stop egg laying, we’ll just keep having grasshoppers,” said entomologist Dan Johnson.
If it rains shortly after the June hatch, it would help control the numbers. If summer is warm and wet, he added, fungal diseases may kill some of them.
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Grasshopper eggs resemble brown rice and are laid in pods containing three to 20 eggs, depending on the species. The eggs survive well because they are coated with an impermeable wax.
There are about 100 species of grasshoppers and while a farmer may find 25 kinds in his fields, only a few are a problem. Farmers need to identify the pests and start appropriate controls before fields are devastated.
“The problem lies with a couple of species and it so happens in the last year one of those species has become predominant,” said Johnson, an Agriculture Canada scientist at the Lethbridge Research Centre.
Johnson showed live examples of the most troublesome hoppers at a recent farmer meeting in Coronation, one of the worst hit areas in Alberta last year.
There are guidelines when scouting fields.
Grasshoppers with red, yellow or orange wings or that make a clacking noise when they fly are not a problem.
In some cases pesticides aren’t recommended because the insects eat weeds rather than crops. For example, the Russian thistle hopper eats weeds such as thistle and kochia. It is green with orange antennae.
“Any grasshopper you see flying before the first of June is not a threat and it has no relevance to the ones that are a threat,” Johnson said.
Grasshoppers flying in August are probably laying eggs. Those that survived winter should start hatching around the beginning of June. If it is cold, they will appear later.
The number of breeding grasshoppers has been high recently and increased in 2002. Rain in late August and starvation in drought zones reduced the number of eggs laid. However, this year’s outbreak should be similar to last year.
“They laid half the eggs they would normally lay, but they were quadruple in number,” Johnson said.
Last year the clear-winged and the two-striped grasshoppers were the enemies.
The clear-winged female is large and brown while the males are smaller. The species flies well and was the main grasshopper seen last year in east-central Alberta. It eats cereal crops.
The young clear-winged grasshopper is ravenous and starts life as a tiny black and white insect. It congregates in dense groups the size of a footprint. Later they are dark brown and scurry into fields.
The clear-winged hatches around June 1-5, but last spring hatchings were delayed because of rain and cool weather.
The two-striped grasshopper eats broad leaf and cereal crops, including canola and lentils. It was the main hopper pest in Saskatchewan last year. It is light brown and small, about two millimetres long when hatched.
Flat-faced grasshoppers do no economic damage. The front of their faces is flat and tilts forward to a point. They have stripes along their sides.
