HYMENOPTERA. 391 
when peace reigns supreme; but they are not more exempt than 
other animals from the necessities and dangers of war. They have 
a great many enemies among the population of the woods; they 

#¥ Fig. 367.—Ant milking Aphides, or Plant-lice (magnified), 
must, then, be prepared to repel their attacks. They display in that 
the most scientific resources of the military art applied to defence. 
It is almost needless to say that sentinels are, at all times, posted 
