Vegetable caterpillar
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Vegetable caterpillars are the result of infection of large underground caterpillars by a fungus of the genus Cordyceps. Species of Cordyceps are found throughout Eurasia and Australia, with centres of diversity in eastern Asia.
It is not certain how the fungus infects the caterpillar, possibly by the caterpillar ingesting a fungal spore or by the fungus mycelium invading the insect through one of its breathing pores. Once inside, the fungus mycelium ramifies through the host tissue, eventually completely consuming it and replacing the caterpillar body with fungal tissue. At this stage, the fungus grows a usually columnar fruiting body that reaches the surface and releases spores.
Vegetable caterpillars are important in Chinese medicine, being regarded as having an excellent balance of yin and yang (through being apparently both animal and vegetable). Assays have found that Cordyceps species produce many pharmacologically active substances. They are now cultivated on an industrial scale for their medicinal value.