Fall defoliator complex
Several species of caterpillars, as well as walkingsticks, were found in September still defoliating deciduous trees. This group is called the fall defoliator complex and each species can increase to high population levels until parasites, disease, predators or unfavorable summer weather reduce their numbers. It usually takes October frosts to kill the remaining adult walkingsticks. Caterpillars of the fall defoliation complex are predicted to increase in l998 because their observed natural enemies (parasites, diseases, predators) were minimal. Walkingsticks won't be back until 1999 since they have a two year life cycle.
The orangestriped oakworm, Anisota senatoria, and the redhumped oakworm, Symmerista canicosta, defoliated about five acres of bur oaks in Morrison County just south of Little Falls. In Todd County, north and east of Little Sauk, the orangestriped oakworm moderately to heavily defoliated about l500 acres of oaks. Another location of large numbers of the orangestriped oakworm was in Benton County, north of Sartel and just west of Watab in S27-T37-R31 where about ten acres of oaks were heavily defoliated. Smaller numbers of yellownecked caterpillar, Datana ministra, was reported defoliating oaks in Chisago County near North Branch. The pinkstriped oakworm, Anisota virginiensis, defoliated about l40 acres of scattered oaks in Crow Wing County on the south side of North Long Lake. It prefers oaks but it also feeds on white birch and other deciduous trees. By September 30th , all the caterpillars had completed their defoliation and had dropped to the ground where they pupate, overwinter, and then emerge as moths next June.
Walkingsticks defoliated about 200 acres of Birch Lake State Forest
deciduous trees in northeastern Stearns County. Walkingsticks lay eggs
until October when killing frosts occur. These eggs drop to the ground
and remain dormant until late May or June of l999 (a two-year cycle). This
insect defoliates many species of deciduous trees but prefers oaks, basswood