Grasshoppers are always a potential threat to barley. Weather and natural enemies are key factors in determining the severity of grasshopper outbreaks year to year. Alberta Agriculture and Rural Development closely monitors grasshopper populations throughout the province, and provides online maps showing problem areas.
Both adult grasshoppers and grasshopper nymphs can cause serious damage to barley crops. Nymphs hatch in the spring and quickly begin feeding on the leaves of young plants, sometimes clipping stems right below the seed head. Adult grasshoppers feed on plant foliage until the first heavy frost before laying their eggs, which overwinter in the soil.
According to Dr. Dan Johnson, a professor of environmental science at the University of Lethbridge who researches biological controls for grasshoppers and other agricultural pests, there are 80 species of grasshoppers in Alberta. Of these 80 species, about 20 can feed on barley leaves, but only seven are actually significant pests. Of the seven, some are found in all parts of agricultural Alberta, and others are regional.
Dr. Johnson has ranked the pest status of each species on a scale of 1 (low pest impact) to 10 (massive impact), and included notes about regional differences, as well as current and recent importance of each species:
|Species||Pest Status Ranking||Description|
|Two-striped grasshopper (Melanoplus bivittatus)||10||Common across Alberta. Feeds on cereals, alfalfa, oilseeds and pastures.|
|Clear-winged grasshopper (Camnula pellucida)||10 (but large variation year-to-year)||Responsible for the crop wipeout in central and east-central Alberta in 2002–2003. Feeds on barley and wheat, but not oilseeds or other broadleaf plants. The number one barley pest in some past years, and it will be in the future, under warmer conditions. They die out in wet years, but their populations shoot to enormous numbers in hot, dry years.|
|Packard’s grasshopper (Melanoplus packardii)||8||Common in Alberta, especially in sandy soil. Feeds on cereals, alfalfa, oilseeds and pastures.|
|Lesser migratory grasshopper (Melanoplus sanguinipes)||10 in the past
|The panic pest of the 1930s. Feeds on cereals, alfalfa, oilseeds, and pastures.|
|Bruner’s spur-throated grasshopper (Melanoplus bruneri)||7 in central and northern Alberta
0 in southern Alberta
|Does not occur in most of southern Alberta. Readily feeds on alfalfa especially, but also cereals, oilseeds, and pasture.|
|Red-legged grasshopper (Melanoplus femurrubrum)||2||Sometimes feed on barley, but they are usually local and over-estimated.|
|Black-winged grasshopper (Dissosteira carolina)||5 in southern Alberta
0 everywhere else
|Localized where soil is finely structure (and possibly drifting). Mainly located in southern Alberta.|
Grasshopper damage and corresponding crop losses are directly related to population density. Grasshopper outbreaks are preceded by two to three years of hot, dry summers and dry falls. This dry weather benefits grasshopper egg and larvae survival and development.
- Scout for grasshoppers along field margins beginning in June, and continuing until the end of August
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