Pine needle scale hatching

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.

In the fall we get a number of calls from growers that have found their Scotch pine covered with pine needle scale. Pine needle scale becomes more visible this time of the year because they have moved to the new growth, and females have matured to the adult state that has the characteristic white, waxy scale cover. Normally, scales overwinter as eggs under this scale covering.

Usually, we have two generations per year – spring and summer. In southern Michigan, we have reports of some crawlers hatching as a partial third generation. In trees that we have observed in northern Lower Michigan, we haven’t found crawlers active, but have found a number of ladybird beetle larva feeding.

Growers thinking about spraying for this partial third generation should keep in mind the following:

  1. These newly hatched crawlers will not survive the winter.
  2. Killing these crawlers will have little effect on the number of white adult females that growers are finding now. They don’t have enough time to develop into adult scales, so you will not see any more white scales than you are finding now.
  3. If you don’t have crawlers present and the scale has the white armor, pesticides will not be effective. Spraying the trees will only suppress predators such as ladybird beetles.

Adult female scale
Photo 1. Adult female scale on Scotch
pine needle.

pine needle scale
Photo 2. Scotch pine needle scale damage.

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