Important to time insecticide applications for pine needle scale
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Applying insecticides at the proper time is a key element in controlling pine needle scale. Pine needle scale is most vulnerable to insecticides during the crawler stage. Although crawlers are tiny, they are readily visible on the needles, especially if you use a hand lens or magnifying glass. The ideal time to apply an insecticide spray is after nearly all the pine needle scale eggs have hatched and most crawlers have reached the hyaline stage. At this point, the young crawlers are exposed on the needles and have not yet started to produce the hard, white armor.
Spring generation eggs hatch in May or early June at roughly 300 GDD50. Usually, eggs hatch within about a week, and most crawlers should be in the hyaline stage by 400 to 500 GDD50. This is the ideal time to apply an insecticide. If the weather cools down, hatching may continue over two to three weeks. Good scouting will help you assess the size of the pine needle scale population in your field, determine whether control is necessary and the best timing for control.