Pine needle scale hatching now in Scotch pines

Pine needle scale is becoming more visible now. Growers thinking about spraying for a partial third generation should keep the following information in mind.

In the fall we get a number of calls from growers that have found that their Scotch pines are 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 stage that has the characteristic white, waxy scale cover. Pine needle scale overwinters as eggs under the female scale covering.

Pine needle scale
Characteristic “white flecking” of adult females on foliage.

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 larvae 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 when the trees are harvested 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.

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