Growers are starting to find more than one species of cutworms in their fields, which makes it more difficult to deal with the pests.
“When we do find a field with high densities, it appears that we’re finding multiple species of cutworms, which we refer to as a ‘complex,’ ” says Jennifer Otani, a pest management biologist with Agriculture Canada.
“We’re also encountering these complexes more frequently than the historical records seem to suggest occur. Growers used to find single species.
“For example, the field would be overrun with either redbacked or pale western cutworm, whereas many of the fields we now visit are occupied by three to five species of cutworms….
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“And we seem to be encountering some of the less common species, like dingy and bristly cutworms in these complexes.”
Additional species add to management issues.
For example, dingy cutworms spend more of their annual life cycle as larvae than pale western cutworms, and it’s the larval stage that feeds and causes damage.
“With dingy cutworms, larvae emerge from eggs in the fall and then overwinter, which means that they exist within a field for multiple months and pupate in mid-July … compared to something like a pale western cutworm, which hatches in the spring and exists in a field for eight-to-10 weeks,” Otani said.
“The presence of dingy cutworms can mean growers are dealing with a longer period of larval activity within their fields.”
