Leaf-insect, or WALKING-LEAF (Phyllium), a very remarkable genus of orthopterous insects, of the family Phasmidae (q.v.), natives of the East
Indian region. The abdomen is flattened out, and covered in the wingless females by a pair of wing-covers which together look exactly like a leaf. The colour is green, and the suggestion of midrib and netted veins is marvellously mimetic. The legs are also flattened, green, and leaf-like. The male has functional wings, but is also remarkably mimetic. As the insects live among leaves, and are sluggish, their detailed resemblance to the surroundings cannot but be usefully protective. The name of the commonest species (P. siccifolium) refers to the fact that when the insects die the green colour changes into that of a withered leaf. See MIMICRY.