A survey of Christmas tree farms in Michigan revealed that 26% of the Scotch pine Christmas trees have one or more shoots injured by the eastern pineshoot borer, Eucosma gloriola Heinrich. Most attacks occurred on lateral branches in the top half of the tree. Only 2% of the observed trees had pineshoot borer injury on the terminal leader. Control except for normal shearing, was not recommended for most plantations.
McKeague, M. and Simmons, G.
"Incidence and Location of Eastern Pineshoot Borer Damage in Some Scotch Pine Christmas Tree Plantations in Michigan (Lepidoptera: Olethreutidae),"
The Great Lakes Entomologist: Vol. 11
, Article 8.
Available at: http://scholar.valpo.edu/tgle/vol11/iss2/8