CH. X.] THE HEMEROBIUS. 189 



easy to believe it when stated, than to know how 

 the author of the assertion could find it out. 



Another enemy of the aphis is the larva of the 

 lady-bird. It is difficult to trace the origin of the 

 popular custom which ensures protection to these 

 insects. In France they are called Betes de la 

 Vierge, or Vaches a Dieu, as if under the tutelary 

 patronage of the Virgin herself. But they really 

 deserve all the protection they receive ; for while 

 they leave our hops and valuable plants uninjured, 

 they destroy the greatest enemy of these vegetables 

 — the plant-louse. " If," says Kirby, " we could 

 only discover a mode of increasing these insects at 

 will, we might not only, as Dr. Darwin has suggested, 

 clear out hot-houses of aphides by their means, but 

 render our crops of hops much more certain than 

 they now are." In 1827, the shore at Brighton, and 

 all the watering places on the south coast, were 

 literally covered with them, to the terror of the in- 

 habitants: they being ignorant that these insects 

 were emigrating after having cleared the neighbour- 

 ing hop-grounds of the destructive aphis. 



It furnishes a subject of serious consideration, as 

 well as an argument for a special providence, to 

 know, that the accurate Reaumur, and other natu- 

 ralists, have observed, that when any kind of insect 

 has increased inordinately, their natural enemies 

 have increased in the same proportion and thus pre- 

 served the balance. 



