First recorded in Canada in 1931 near Oakville, Ontario, and has not spread naturally much beyond there. There were light infestations in other parts of Ontario in the 1970s and one in southern Quebec in 1940. [Insects of Eastern Pines, Rose, Lindquist and Nystrom 1999, Canadian Forest Service Publ. No. 1313]

There was a small localized outbreak in 2006 here in Fredericton. I discovered larvae dropping to the surface of a trampoline in my backyard in September. (Sawflies normally drop to the ground to pupate, and if the trampoline had not been there, I would not have seen them.) A few were collected and raised on pine saplings in the lab at CFS. According to experts here, they may have arrived on infested nursery stock.

This larva was found near pines behind the nursery at the Canadian Forest Service - Atlantic Forestry Centre and positively identified by a Canadian Forest Service scientist. [edit 9Oct08]