The use of this fungus was relatively unknown in this country until it was credited for the success of Chinese women athletes at the National Games in Beijing, in 1993. Their coach, Ma Zunren, attributed the runner's success to intensive training as well as a stress-relieving tonic prepared from the caterpillar fungus. However, after years of study, it was found that it really is a fruiting body produced by the fungus, Cordyceps sinesis , on dead caterpillars of the moth Hepilus fabricius . When the caterpillar dies the fungus produces a stalked fruiting body that produces spores. The spores are spread in the wind to the next generation of caterpillars.
Uninfected caterpillars pupate into relatively large primitive moths.
The moth is found in the south central Provinces of Guizhou, Hubei, Gansu, Qinghai, Shanxi, Sichuan, Sizang, Yunnan, and Zhejiang. Infected caterpillars are often found in soft soil under trees in mountains over 4000 m high, or in cold, well-drained grassy marshlands. The life cycle of uninfected moths takes two years to complete. Most other moths have shorter life cycles. Hepilus fabricius and other species of Hepialus live in vertical tunnels in the soil and emerge at night to feed on roots or aerial portions of plants.