Warm Weather and Pest Populations

By John Tooker, Penn State Entomology Specialist

And this early warmth has most of the state 100 degree-days or so ahead of average (Fig. 1) and will no doubt push some early season pests to be active earlier than normal. In fact, we have had our first reports of cereal leaf beetle adults being active in the south-central part of Pennsylvania and we expect reports of alfalfa weevil larvae feeding any day now.

The bottom line, however, is that the influence of these temperatures on the majority of crop pests we face is not very predictable. For example, many insect pests that we face (e.g., potato leaf hopper, black cutworm) are migratory and come to Pennsylvania from southern states; therefore, our local weather will not influence their arrival much. To be certain of what is in your fields and understand local pest populations, growers will need to rely even more on regular bouts of scouting—get out in the field and see what is active! To direct this scouting effort, check the PA-PIPE (Pennsylvania Pest Information Platform for Extension and Education)

system (http://extension.psu.edu/pa-pipe ; follow the link and then choose the Public Map link to see the models), which can be used to track degree-days and expected development of some relevant pest species.