Abstract
The first North American collection of the European pine sawfly, Neodiprion sertifer (Geoff.), was made in Somerset County, New Jersey, in 1925 (Hamilton, 1943). It was first recorded in Canada near Windsor, Ontario, in 1939 (Raizenne, 1957), and by 1946 it had spread as far east as London (Watson, 1946). This serious pest of pines has continued to spread, and is now found throughout most of southwestern Ontario (Fig. 1) (Sippell and MacDonald, 1958). This is the only infestation of this species in Canada.