Ich*neu"mon (?), n. [L., fr. Gr. &?;, lit., the tracker; so called because it hunts out the eggs of the crocodile, fr. &?; to track or hunt after, fr. 'i`chnos track, footstep.] 1. (Zoöl.) Any carnivorous mammal of the genus Herpestes, and family Viverridæ. Numerous species are found in Asia and Africa. The Egyptian species (H. ichneumon), which ranges to Spain and Palestine, is noted for destroying the eggs and young of the crocodile as well as various snakes and lizards, and hence was considered sacred by the ancient Egyptians. The common species of India (H. griseus), known as the mongoose, has similar habits and is often domesticated. It is noted for killing the cobra.

2. (Zoöl.) Any hymenopterous insect of the family Ichneumonidæ, of which several thousand species are known, belonging to numerous genera.

&fist; The female deposits her eggs upon, or in, the bodies of other insects, such as caterpillars, plant lice, etc. The larva lives upon the internal tissues of the insect in which it is parasitic, and finally kills it. Hence, many of the species are beneficial to agriculture by destroying noxious insects.

• a large North African mongoose, Herpestes ichneumon; the Egyptian mongoose
  
• the ichneumon fly