Predicting how the warm winter will affect populations of pests this year is not easy, says Ada Szczepaniec, South Dakota State University Assistant Professor and SDSU Extension Entomologist.
"It depends largely on particular pest species and their biology," Szczepaniec said. "For example, insects that overwinter above ground are more likely to be affected by warmer winter weather than insects that overwinter below ground, where temperatures do not fluctuate as much."
Szczepaniec adds that insects develop based on temperature, and will become active earlier if temperatures are significantly warmer during winter and spring months. However, if there is no source of food or large temperature swings occur after insects break dormancy, they will likely incur high rates of mortality and may not become any greater threat to the crops than any other year.
"One thing is certain, however, scouting should start early this year, and we should monitor closely what pests are reported in the southern portions of the state as the migrating pests come in," Szczepaniec said.
Specific insects Szczepaniec says growers should monitor their fields for include; alfalfa weevils, cutworms, blister beetles, wheat aphids and grasshoppers.
"Cutworms, particularly in the northwestern part of the state, may become active soon, if they have not shown up in fields already. Jonathan Nixon, SDSU Extension Entomology Field Specialist with the Rapid City Regional Extension Center reported that grasshopper populations have been unusually high for this time of year in the western parts of South Dakota. Because larvae of blister beetles feed on grasshopper eggs this will mean greater numbers of blister beetles in alfalfa fields," she said. "In the coming weeks, scouting for wheat aphids should also intensify, as they are likely to start to infest fields in early to mid-May this year."
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