Jack pine budworm egg mass surveys were completed on August 5th in Region I. Twenty-nine eggmass plots were sampled in southwestern Beltrami, Hubbard and eastern Becker Counties. Only one eggmass was identified and it was parasitized. An average of one eggmass per plot can indicate low budworm activity the next year. So next year, it's very likely that budworms will again be really hard to find in jack pines. Reviewing past issues of this I&D newsletter (back to the late 1970's), we noticed that through the mid-1980's jack pine budworm occupied a large part of the reporting space. Since that time it has taken a "back seat" to other species of forest pests. In fact, it's more like a "rumble seat."
Large numbers of introduced pine sawfly larvae caused noticeable defoliation on white pines in scattered plantations and yards in Crow Wing and Morrison Counties by mid-August. There are three generations per year and, occasionally by late October, there can be a buildup of needle-consuming larvae.
As a larva, it has a black head, black legs, and numerous yellow and white spots on a dark brown or black background body color. When it grows to about one inch long, it spins a brown, egg-shaped cocoon. Cocoons can be found among the needles, at bases of small branches, on the trunk, on non-host trees, shrubs, grasses, or other objects on the ground. The adults cut their way out of cocoon ends and are fly-like in appearance, but they have four transparent wings, black heads and yellow to black abdomens. Eggs are deposited serially in slits cut in the edges of old needles by the female's sawlike ovipositer. About ten eggs may be found on one needle, and each female may lay more than one hundred eggs. Larvae emerge in ten to fourteen days.
Introduced pine sawflies overwinter as larvae in cocoons that are protected from killing temperatures by being formed in the leaf litter on the ground or on tree trunks below the snow line. Natural control is caused by insect parasites, predators and low winter temperatures. Predators include insects, spiders, rodents which burrow in the leaf litter, chickadees and other birds. Various chemical insecticides provide control of the larvae.