Forest Insect and Disease Newsletter

Forest tent caterpillar in west-central and central counties

image: Defoliation of basswood and new growth after that.With the unseasonably warm weather, the oak and basswood leaves are unfurling early: up to a month earlier than normal. Will this "throw a curve ball" to the tiny but voracious forest tent caterpillars? Not likely. Similar to their food source, FTC phenology is base on the local weather. That way, the vagaries of weather before they hatch won't affect the caterpillars too much. Once they hatch, FTC have formidable staying power; they can survive nine days without eating. So, if leafout is temporarily delayed, they can wait. However, if the young leaves are killed by a hard frost, caterpillars will starve.

image:Oak defolication by FTC 2011 was the fourth year of the outbreak and 41,400 acres were defoliated. See map. Normally, FTC populations build up in small areas and decline rapidly, often within 2 years. That's not the case this time, some localities have had three and four years of defoliation. We expect to see continued FTC activity in 2012. There might be some oak and basswood mortality associated with this outbreak.

All sorts of information about FTC, from biology and ecology to management, is available online.

image:2011 defolication by forest tent capterpillar