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The genus Cordyceps known as an insect parasite forms a sclerotium in insect bodies and then produces perithecia on the single or multiple stromata produced from sclerotium. Collected Cordyceps were identified into 5 species: Cordyceps militaris, C nutans, Cordyceps sphecocephala, Isaria japonica, and Tonubiella sp. The fruit bodies of Cordyceps in petri-dish cover were fixed by tape and put the lid on water agar plates to isolate these collected Cordyceps. The germinated spores were transferred from water agar to Potato dextrose agsr(PDA) after six hours. Mycelial growth of C. nutans and C. militaris was the most successful on Hamada media and was also good on Complete media and PDA. Mannose as a carbon source was good for two species and Glutamic acid as a nitrogen source was satisfactory to C. militaris and Asparagine gave a goad result to C nutans. C. militaris and C. nutans showed similar mycelial growth rate on the media that contained thiamine-HCl, biotine or nicotinic acid as a vitamine. When conidia of C. nutans were inoculated to insects, mortality was high in Anogeia napi L, Hemiptera, Plutella xylostella and 50% in Orthoptera, 12% in Acantholyda posticalise M, but not Agelastica coerulea B. in Aphididae, C. nutans was collected from only Hemiptera in nature, but killing effect on other insects was proved. Mycelial growth and fruit-body formation were good on the media that consist of rice powder 5 g, wheat flour 5 g, water 100 ㎖, but formed fruit-body was not complete stromata but a mass of conidia according to results of observing microscope.
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