Cankerworms finally trickling out

Over the past week or so I have found cankerworms here and there. A few on a maple along the greenway. A couple dangling from a willow oak on campus. Today I found a small cankerworm tromping across some gloomy scales.

Cankerworms on a gloomy scale-infested red maple trunk. Photo: SDF

I past years I have seen cankerworms hatching in mid-March. In 2015 they hatched April 7 but even so they all hatched at once.

After a very early spring snow covered plants that had already started flowering and growing new leaves and shoots. Photo: SDF

I wonder if the snow we had on March 12 this year, around when I thought cankerworms would be hatching, might have killed some. Leaves and flowers on many trees and shrubs had already flushed and were damaged by the snow. Maybe cankerworms were about to hatch and were in a vulnerable state.

Cankerworms feeding on maple leaves. Photo: SDF

Alternatively, it could just be a low cankerworm year. Cankerworms live in New England and Canada so it is hard to believe a little snow would hurt them. I did not monitor adults this year but my friend Derek Johnson at VCU probably did. His lab just published a new threshold relating adult captures to likelihood of defoliation by larvae.

In any case, here they are we will see how the population develops.

2017-06-16T08:42:28-04:00 April 6th, 2017|Categories: Uncategorized|

About the Author:

Steve Frank
I am broadly interested in the ecology and management of arthropod pests. Herbivorous arthropods cause extraordinary damage to plants in agricultural, urban, and natural ecosystems. Understanding interactions between pests and their environment, plant hosts, and natural enemies can improve management practices and reduce pesticide applications.