No apparent toxicity resulted from feeding nestling birds 25-50% of their body wt. daily of insects sprayed with DDT at 1 lb. per acre when the rest of the diet consisted of food provided by their parents. A 20% mortality from DDT toxicity resulted among nestlings brought into the lab. and fed entirely on the sprayed insects. It was concluded that the spraying operations against spruce budworm at Lake Clear Junction, N. Y., in 1946, in conjunction with which this expt. was conducted, had no detrimental effect on the nestling birds in the area, inasmuch as sufficient insect material remained available to them. It is assumed, however, that if a large forested area were treated with DDT at a rate sufficient to eradicate the insect population when nestlings are being fed, they would suffer or succumb from DDT toxicity itself or from a combination or weakness and toxicity.