Forest Insect and Disease Newsletter

Forest tent caterpillar in the Northeastern Region

image: Forest tent Caterpillar egg mass

Egg Mass of Forest tent caterpillar.

One mass contain 100 to 350 eggs.

Forest tent caterpillar (FTC) defoliation was mapped during the aerial survey in Pine, Aitkin and Crow Wing Counties.  A few small areas of defoliation were also mapped in Itasca, Carlton, St Louis and Lake Counties but there were many reports of caterpillar sightings.  Last year was certainly not an outbreak year in the northeast, but how about this year? Will it be safe to go in the woods, have picnics, camping trips or even outdoor weddings?

Based on the low numbers of egg masses found in most locations, it's looking like this year will be similar to last year. An egg mass or two were found in a couple of spots but no egg masses were found on the majority of  egg mass survey plots.  The one exception to this was that enough egg masses were found in the parking lot of the Burning Tree Plaza in Duluth.  Since surveying for FTC egg masses usually involves cutting down three trees and counting all the egg masses in the crowns, some Forest Health survey work is best done late at night, for obvious reasons. Of course with the FTC population low and spotty in the NE, searching for egg masses would be expected to be very hit or miss. Likely there will be some scattered locations that experience noticeable defoliation this next summer while most of the Region will see little or none. 

With the early spring followed by freezing temperatures, cold rains as well as snow, additional questions might be whether the FTC eggs hatched early and did the caterpillars survive?  As of April 20, the egg masses had not yet hatched near Nisswa in Crow Wing. Some clones of aspen had begun to leaf out before the cold weather and snow. A few of the small leaves have browning on the edge, but most of the leaves appear to have suffered no damage at all. So at least for now it appears that both our caterpillars and leaves are safe and sound waiting for the snow to melt and warm temperatures to return.