from the book, "Our Fascinating Earth"
During the 1950s Hollywood ran wild in its science fiction renderings of giant insects, giant reptiles, and other huge creatures. (The ultimate may have been attained when a film was made about "killer tomatoes.") But reality can be stranger than fiction, and killer mice are a good example.
The name of these rodents was not derived from a bad horror movie but from their very real nature. There are three species of killer mice, Onychomys sp., often called grasshopper mice since grasshoppers are their preferred food. Onychomys are fairly common and widespread in the central and western United States. They look like ordinary field mice — brownish, small, with big ears and long whiskers. Taxonomically they have been classified as murids, which makes them members of a common family of normally vegetarian mice. What they do, however, is anything but normal or vegetarian.
The grasshopper mice are ferocious predators — in miniature of course. They hunt by night in large packs, seizing their hapless prey and tearing it limb from limb in a matter of seconds. Nor does the carnage stop there. When the prey is abundant, they raise their pink—tipped noses in the air and howl like tiny wolves — apparently calling their friends and relatives to join the feast.
As their name implies, these killer mice are most partial to a grasshopper dinner, but a furious appetite added to a lust for killing causes more than insects to become their prey. They will not hesitate to launch a mass attack on field mice, lizards, or any other small animal that blunders into the path of the hunting pack!
Not surprisingly, farmers regard the grasshopper mouse — the scourge of grasshoppers, cicadas, caterpillars, moths, beetles, and small rodents — as a welcome intruder. With 95 percent of its diet consisting of insect or animal food, the grasshopper mouse not only spares crops but also eliminates crop destroyers with incredible efficiency. So the killer mice are to be doubly praised.