Will this winter’s cold temperatures reduce pest populations in your crops next year?

The cold winter thus far has prompted many folks to ask what the influence of these temperatures might be on insect and slug populations. 

It certainly is the case that harder winters will knock back the populations of some pest species — bean leaf beetle, cereal leaf beetle and slugs are three that jump to mind.

Expect populations of these pest species to be lower than usual come spring. (For slugs, their survival is also influenced by the amount of snow on the ground, higher amounts of snow insulate against colder temperatures.)

But, as for most issues with insects, it is difficult to generalize and the influence of cold winter 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, armyworms) are migratory and come to Pennsylvania from southern states; therefore, our local weather will not influence their arrival much — their local overwintering conditions matter more.

For pest species that have arrived more recently, we have a relatively poor understanding of the influence of winter temperatures on their populations.

Brown marmorated stink bugs, for example, seems to have higher mortality the colder it gets, but their overwintering site likely influences their survival.

If stink bugs are able to find just the right overwintering spot that keeps them cold but not too cold, they will probably make it through the winter. 

For an even newer pest like kudzu bug, which is on the verge of being in Pennsylvania (http://extension.psu.edu/plants/crops/news/2013/07/kudzu-bug-an-approaching-pest-species), we will soon find out how well they survive the cold temperatures. 

Luke Fritz is executive director of the Butler County Farm Service Agency.