THE Cows THAT ANTS MILK 23 



field-voles, can hardly be combated with any hope 

 of success ; while locusts and Colorado beetles 

 devastate our crops with practical impunity. 



When it comes to aphides, we are quite unable 

 to cope with the infinite numbers of our infini- 

 tesimal foes; and if we take the microscopic 

 creatures which cause cholera, typhoid fever, and 

 other zymotic diseases, we may keep out of their 

 way, it is true, or may isolate the objects in which 

 they breed and store their germs, but we are 

 practically without means to kill or hurt them. 

 The larger the foe, the more easily is he met ; the 

 smaller our enemy, the more difficult is he to 

 extirpate. We killed off the American buffalo (or 

 bison) in a single generation ; a thousand years 

 would probably fail to kill off the insignificant little 

 aphides that infest our roses. 



In the case of one member of the family at 

 least the experiment has been tried on a gigantic 

 scale in France, and as yet with comparatively 

 small results. For the dreaded phylloxera which 

 attacks the vines is, in fact, an aphis ; and though 

 immense rewards have been offered by the French 

 Assembly for any good remedy against phylloxera, 

 the only successful plan as yet proposed has been 

 that of planting healthier and sturdier American 

 vines, which resist the little beast a good deal better 

 than the effete and worn-out European species. 

 But many other members of the family wage war 

 with distinguished success against the British farmer. 

 The little black "colliers" which attack our bean 



