Frass-drop Studies of Larvae of Neodiprion americanus banksianae Roh. and N. lecontei (Fitch) (Hymenoptera: Diprionidae)

Among others, Schwerdtfeger, 1931, Gosswald, 1934, and Morris, 1949, have used frass-drop samples as indirect measurements of the density of forest insect populations with some success. The method has also been used to assess the effects of various insecticides on the feeding of treated larvae (Rhumbler, 1929; Schwerdtfeger, 1930) and to study the influence of weather upon the feeding and development of forest insects (Monro, 1935).