Striped pine or tortoise scale?
Editor’s note: This article is from the archives of the MSU Crop Advisory Team
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Pine tortoise scale (Toumeyella parvicornis) adult female scales are reddish-brown whereas stripe pine scale (Toumeyella pini) is similar in appearance, but has distinctive white stripes. For many years, both of these soft scales on Scotch pine were called tortoise scale, but a scale expert finally made separation of the two species possible in the mid-1990's.
In Pennsylvania, they found most of the scale in Christmas tree farms are actually striped pine scale. After looking at scales this past week, I suspect this is true for Michigan as well. What does this mean…probably nothing to a grower since the biology and control of the two species are quite similar with a single generation each year. Also, there doesn’t appear to be much difference in timing of crawler emergence, which is now in many locations in the lower peninsula. Crawlers are tan to pink and resemble sawdust as they move over the bark. These scales produce lots of honeydew, which is attractive to ants, bees and wasps. This honeydew also supports growth of sooty mold, and heavily infested trees appear to be black.