A native defoliator of hardwoods, especially aspen, basswood, oak, birch, and willow, forest tent caterpillar populations peak every 10 to 16 years in Minnesota. 

According to the Department of Natural Resources, these FTC populations could be building toward a 2014 or 2015 peak.

This summer, 274,000 acres of defoliation were mapped during the aerial detection survey and showed:

• From Beltrami and Lake of the Woods Counties to Cook County, aerial survey was delayed by two months and very few acres with FTC were mapped, so we really don’t know how extensive FTC populations were. More information will be known next year.

• A dozen 60-acre pockets of defoliation were mapped in Fillmore and Houston Counties; a rare occurrence for this area.

• Far from declining, the FTC populations in west-central counties are going strong. There basswood and oaks are the primary targets and both species might be in trouble of declining in 2013 due to the duration of the local outbreaks.

Speaking of big acreages of defoliation, Cass County had the three largest polygons this year: 14,113; 6671; and 5975 acres.