These surveys were designed to know decreasing rate of cocoon production all over the country and purchased amount of cocoons at public market which had been caused by various diseases in autumn of 1975. The results can be summarized as follows; 1. Percentage of sericuitural houses which sustain disease damage was 18.5 percent, and cocoon yield per box in bad crop houses was 8.8kg smaller than that in normal houses. 2. About 838M/T of decreased cocoons and 5.6 percent of damaging rate can be estimated in this autumn throughout the country. 3. In our country, it was 40.9 per cent of Grasseril and 34.5 per cent of Flacherie of silkworm diseases.