Gypsy moth survey

By Peter M. Dziuk, Program Coordinator
Plant Protection Division
MN Dept. of Agriculture

With over 98% of field reports in, we have a pretty good picture of gypsy moth activity in Minnesota for 1999. This year has had more than it's share of surprises.

The most welcome surprise is a dramatic decline in moth catches through all of the southeastern counties and the seven-county Metro area. An early prediction that the wet, cool May and June might have an adverse affect on small start up populations is no longer just wishful thinking. The southeast regional catch plummeted from last years high of 628 male moths to a mere 83 this season. The Metro declined from 287 moths last year to just 71 moths this year.

Over all there were also fewer catches in nurseries this year with the exception that infested stock at one location provided an unprecedented catch of 35 moths. An emergency action notice and compliance agreement will be in place until treatments can be implemented next spring.

An unwelcome and also curious surprise was large numbers of moths caught all up and down the North Shore area of Lake Superior. This region has a long history of only producing one or two odd moths a year and those usually in Duluth. Starting at Jay Cook State Park in Carlton County and then clear up to Judge Magney State Park almost at the Canadian border, 67 moths have been caught. Suggesting moth blow is premature and very unlikely at best. Wisconsin counties across the lake have barely produced as many moths themselves. More likely are burgeoning gypsy moth populations in Milwaukee, northwestern Illinois, etc. that are hitchhiking out with tourists who are increasingly traveling to northern Minnesota for their summer getaways.

Finally, most of the western border counties were surveyed at a trap density of one trap per four square miles. Not surprisingly, no moths were caught in any of the survey areas. A number of these counties had not been trapped since the late eighties and probably will not be trapped in a major survey for another six to eight years.

A final report of this year's program will be provided after all trap data has been reviewed.

1999 Minnesota Gypsy Moth Catches by County