According to the phenological indicator system we use to predict when important events in the life cycle of insect pests will happen, the pine needle scale eggs should start to hatch this week or next. This common scale insect, found on pine and spruce trees, primarily spends the winter in the egg stage. The eggs hatch in mid-May and the tiny first instar nymphs, called crawlers, move about before settling to feed and develop in the same spot for the rest of their lives.
Because the crawler stage is vulnerable to insecticides, including soapy water and horticulture oil sprays as well as traditional insecticides such as diazinon, Orthene, malathion and Sevin, it is important to know when the eggs hatch. Close observational work done over the years has shown the pine needle scale egg hatch coincides with the bloom of Vanhouttei spirea, horse chestnut and Zabels honeysuckle. These events usually closely follow full bloom on common lilac, so now is the time to get ready to treat pines for scale if necessary.
This article originally appeared in the May 13, 1992 issue, p. 79.