1. This investigation had been made into by the writer, Kim Jae Wun from the 20th Jan. in 1968 to the 29th of Jan. in 1968. 2. I investigated the standing crops of aquatic insects in the eastern and western part centered around the Taibaik mountain range. 3. The western part is called the streams of Chunchon, Hongchon, and Wunju Districts. The eastern part, the streams of Yungyang, Kangnung and Samchuk Districts. 4. In the western part I collected Table 1. Each order is as follows. Plecoptera……7.4% Ephemeroptera……22.8% Tricoptera……16.8% Diptera……52.7% Other orders……0.3% 5. In the eastern part I collected TableII. Each order is as follows. Plecoptera……14.6% Ephemeroptera……11.3% Tricoptera……66.4% Diptera……1.3% Other orders……6.4% 6. In the western part Diptera (52.7%) are overwhelmingly major. In the eastern part Tricoptera (66.4%) are major. 7. Dominant species of the western part are Tipula sp. Ta. Those of the eastern part are Stenopsyche griseipennis. 8. The waste water from a Iron mine of the Yungyang District, on the one hand, enabled aquatic insects not to live there, much less fishes. On the other, the waste water made it impossible for the inhabitants of the district to utilize the stream. Therefore the damage of th crops is great.