The order Hypocreales contains certain fungi which are parasitic on other fungi, and also on insects. In the genus Cordyceps there is a club-like form about an inch long, and of a rich red colour, which lives as a parasite on the pupae of various moths buried beneath dead leaves. In New Zealand a similar fungus lives on caterpillars.
The mycelium in time replaces the body, but maintains outwardly the form and appearance of the caterpillar. These growths are much prized by the natives as food. The form which grows on the truffle-like Elaphomyces is shown in the species of Elaphomyces upon which the Cordy-ceps lives as a parasite grow two or three inches below the surface of the ground, and somewhat resembles a truffle in appearance.