• Sayce, Clyde S.
  Fisheries Biologist
  

The insecticide Sevin (1-naphthyl N-methylcarbamate) has been used on orchard, garden, and field crops for control of a wide variety of insect pests, and on forest trees near Willapa Bay to control the defoliating Hemlock looper Lambdina fascellaria lugubrosa. It was first used in marine waters in combination with a heavy oil (orthodichlorobenzene) to rid oyster grounds of oyster drills (Loosanoff, Mackenzie, and Shearer, 1960). Butler, Wilson, and Rick (1960) showed that Sevin had a threshold inhibition level of 1.0 ppm on growth of the oyster Crassostrea virginica. Davis (1961) found that Sevin had a moderately adverse effect on the growth of eggs and larvae of the oyster C. virginica and the hard clam Venus (Merccenaria) mercenaria, and Haven, et al. (1966) showed that Polystream and Sevin did not control adult oyster drills (Urosalpinx cinerea) or its egg cases, while having a deleterious effect upon the natural community.