Olesicampe benefactor Hinz and the Bavarian strain of Mesoleius tenthredinis Morley, European ichneunionid parasites of the larch sawfly, Pristiphora erichsonii (Hartig), were introduced into northern Minnesota from Manitoba in 1971 and 1972. Both species are now established. There was also natural spread of 0. benefactor into Minnesota from Manitoba releases in 1961 at a point ca. 200 miles northwest of the Minnesota plots.
Kulman, H M.; Thompson, L. C.; and Witter, J. A.
"Introduction of Parasites of the Larch Sawfly in Minnesota,"
The Great Lakes Entomologist: Vol. 7
, Article 6.
Available at: http://scholar.valpo.edu/tgle/vol7/iss1/6