Forest tent caterpillar
As of June 22nd, aerial survey has detected very spotty FTC defoliation in Aitkin, Cass, Crow Wing, Douglas, Kandiyohi, Meeker, Mille Lacs, Stearns, Todd, and Wright Counties. Again this year, the caterpillar's primary host was basswood but defoliation was also noted on aspen, birch and oak. Caterpillars are blue-black, covered by brown hairs and they have a line of whitish spots along their backs that resemble foot prints or key holes. By June 17th, they had formed tents of a few leaves held together by silk threads.
Inside these tents, the caterpillars had spun yellow cocoons and changed
into pupae. Buff-colored moths with two darker oblique bands on the forewings
will emerge about ten days later. Some natural controls were observed at
scattered populations, but two or more years may pass before collapse of
this forest pest occurs. Natural controls include bacteria, fungi, viruses,
large gray flies, certain wasps, predatory beetles, ants, tree bugs, spiders,
and birds. Since caterpillars completed their feeding damage by mid-June,
trees have time to refoliate and minimize the impact of spring defoliation.
|Rosy maple moth
spreads across east central Minnesota
Large numbers of moths with bright yellow bodies, light yellow wings with pink forewing patches and a single pink stripe on the rear wings were seen around lights in Cass, Crow Wing, Kanabec, and Isanti Counties from May 19th to May 30th.
Our mild winter and warmer spring temperatures probably caused early moth emergence from pupae that overwintered in the ground litter.
Rosy maple moths lay eggs on the underside of red and sugar maple leaves. The caterpillars that hatch from these eggs are called greenstriped maple worms and have two recurved black horns just behind their heads and black spines arranged in two rows along their bodies. Scattered heavy maple defoliation is predicted during July and August. Heavy red maple defoliation occurred at one location north of Brainerd in late July of 1997, but this pest was not observed elsewhere last year. Natural controls include fungi, bacteria, insect and other parasites, birds and small mammals.