ON EPIDEMICS AMONGST MICE. 305 



berries. Beech-mast and nuts, corn, turnips and potatoes are badly attacked 

 by them. When the corn begins to ripen they assemble in hordes in the 

 fields, bite the stalks through at the base till they fall over, then gnaw 

 them through above, and drag the ears into their burrows. During the 

 harvest they follow the steps of the reapers from one crop to another, devour 

 the corn that has dropped among the stubble, gather the ears up which 

 have fallen in binding up the sheaves, and at last find their way to the 

 stackyards, where they find provision for the winter. Tn the woods they 

 collect the fallen haws, juniper-berries, beech-mast, acorns, and nuts in 

 their burrows. During the hardest weather they fall into uninterrupted 

 hibernation, but when milder weather returns they rouse up, and feed on 

 their stores. They are incredibly voracious, and require much to satisfy 

 them, but they cannot do without water. 



" Field Voles are very gregarious, and live socially together, at least 

 in pairs, but more commonly in great hordes, and therefore they link 

 one burrow to another. They multiply with extreme rapidity. Even in 

 April we find from four to eight young in their warm nests, which lie from 

 40 to 60 cm. below the surface of the ground, and are softly lined with fine 

 fragments of hay or straw and moss ; and in the course of the summer 

 the female produces young from four to six times more. It is highly 

 probable that the young of the first brood are themselves ready to breed 

 in autumn, and the amazing increase in their numbers is thus easily 

 explained. 



11 ' Under favourable circumstances,' says Blasius, ' the Field Vole 

 multiplies in an incredible manner. Many instances are known in which 

 a large part of the harvest has been destroyed over large tracts of country 

 by their inordinate increase, and more than a thousand acres of young 

 beech trees have been destroyed by their gnawing the bark. Those who 

 have never experienced such a vole-year can hardly form a conception of the 

 almost incredible swarms of mice in the fields and plantations. They 

 often appear in a particular neighbourhood without their gradual increase 

 having been observed, as if they had suddenly come upon the earth by 

 magic. It is possible that they sometimes migrate suddenly from place to 

 place. But their rapid multiplication is generally foreshadowed for weeks 

 beforehand by the increase of the Buzzards (Mciusebussarde). During 

 the twenties, the Lower Rhine was repeatedly visited by such a plague. 

 The fields were so undermined in places that you could scarcely set foot on 

 the ground without touching a mouse-hole, and innumerable paths were 

 deeply trodden between these openings. On fine days it swarmed with 

 voles, which ran about openly and fearlessly. If they were approached, 

 from six to ten rushed to the same hole to creep in, and unwillingly 

 impeded each other's progress by crowding together. Tt was not difficult 

 to kill half-a-dozen with one blow from a stick in the crush. All seemed 



