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Grassland and Forage Insects

A new project for study of grassland and forage insects was set up after the war and assigned to Filmer. Surveys to determine insect populations on forage crops found that pea aphids were causing serious damage to alfalfa; spittle bugs In the central part of the state were causing serious damage to first cutting of clover and alfalfa; and potato leafhoppers were causing serious damage to second and third cuttings of alfalfa. In the case of the pea aphid and the spittle bug, it was determined that a single insecticide application gave control, and that in the elimination of pea aphids forage yields increased from 30 to 80 per cent. The potato leafhoppers in New Jersey arrive each summer from the south and do not over-winter in the state. Applications of residual insecticides were found to give excellent control of this pest.

Surveys on the Hessian fly have been conducted for several years in grain-producing areas. This insect can be controlled by adherence to planting dates, but infestations have ranged from 5 to 40 per cent, largely from failure to observe the "fly-free date." The recent use of small grains for fall and spring pastures, and the planting of wheat as a cover crop without regard for seeding date or time that the cover crop is plowed under, are both instances where Hessian fly has increased from planting without regard to the "fly-free date."