vole name for a large number of mouselike rodents , related to the lemmings . Most range in length from 3 1/2 to 7 in. (9-18 cm) and have rounded bodies with gray or brown coats, blunt muzzles, small ears concealed in the long fur, and short tails. They are found in a wide variety of habitats. Of the approximately 70 vole species, over 40, distributed throughout North America, Eurasia, and North Africa, are classified in the genus Microtus. These voles typically make runways under dense vegetation or shallow burrows in the ground. They feed chiefly on grasses but also eat bark, leaves, seeds, and insects. They are known in North America as field mice or meadow mice (the Old World field mice are not voles). Like lemmings and various other small rodents, these voles periodically undergo population explosions which cause them to swarm over the countryside. Of similar distribution are the five species of red-backed voles, genus Clethrionomys, which spend much of their time in shrubs and bushes. Species of the North American genus Phenacomys nest in trees and are known as tree mice or lemming mice. The sagebrush vole, Lagarus curtatus, is found in the W United States. Other Lagarus species, found in S Russia and Mongolia, are misleadingly called steppe lemmings. The water vole, Arvicola, of Europe and W Asia, is a large, semiaquatic vole, somewhat resembling the closely related muskrat . Voles are classified in the phylum Chordata , subphylum Vertebrata, class...