There are about one thousand fungal species capable of killing insects, most of which are ascomycetes.The species like Metarhizium spp.and Beauveria bassiana has been developed as environmentally friendly bioeontrol agents against different insect pests.The species like thecaterpillar fungus Ophiocordycep ssinensis and Cordyceps militaris, however, have been used as traditional Medicines for hundreds of years, especially in Eastern countries.