Smithsonian Report, 1941. — Criaghead 



Plate 10 



1 . AUTOGIRO IN ACTION SPRAYING CONCENTRATED OIL-LEAD ARSENATE MIXTURE 



OVER Red Pine Plantation Infested with Neodiprion sertifer. 



2. larvae of the European Spruce Sawfly (Diprion polytomum) massed 



UNDER THE TREES They HAVE DEFOLIATED. 



These larvae fall to the ground after the foliage is consumed in their search for additional food. 



