Our two major pests of pine trees should be controlled now if population densities warrant treatment. European Pine Sawfly larvae will become more noticeable as they rapidly approach their 1-inch length. Of course, feeding damage to the old needles by the clusters of gray-green "worms" also becomes more noticeable the longer you wait. Mechanically remove or prune away larvae, or spray with Sevin, Orthane or horticultural oil (the last choice most effective against small larvae).
Lilacs have bloomed and spirea is in bloom, so Pine Needle Scale eggs should be hatching. The first instar nymphs ("crawlers") are vulnerable now to sprays of horticultural oil, insecticidal soap, Diazinon, Orthene, Sevin, and other labeled insecticides.
This article originally appeared in the May 22, 1991 issue, p. 95.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on May 22, 1991. The information contained within may not be the most current and accurate depending on when it is accessed.