ORDERS OF INSECTS. 175 
and are produced in great numbers at particular times of the 
year. They then quit the nest and pair, after which the fecun- 
dated females lose their wings and form fresh societies. The 
workers (fig. 90, ) are sometimes all of one kind, but they are 
often divided into two, or even three, distinct classes or ‘‘ castes.” 
The Ants exhibit many most extraordinary and interesting in- 
stincts and habits, of which their custom of “ milking” the little 
Plant-lice has been already mentioned, Another very singular 
habit of some Ants may be just alluded to—their habit, namely, of 
capturing the pupz of other species of Ants and bringing them up 
as slaves, The relations, however, between the masters and slaves 
vary a good deal in different cases. In the case, for instance, of 
the Russet Ant (Formica rufescens) the masters are so entirely 
Fig. 90.—The Red Ant (Myrmica rufa), a Winged male; 
4 Wingless female. Magnified, 
dependent upon their slaves that they cannot even feed them- 
selves, and the only work which they perform unassisted is the 
capturing of fresh slaves. In the Blood-red Ant (Formica 
sanguinea), on the other hand, the slaves are much fewer in 
number, and the masters are much less dependent upon their 
good offices. In all cases, the slaves exhibit the greatest 
devotion to their masters, and are invariably taken the greatest 
care of by their captors, : 
ORDER XI. STREPSIPTERA-—This is an extremely small 
order of insects, which merely requires to be mentioned. It 
includes only certain minute parasites, which are found on bees 
and other Lymenoptera. The females are destitute of wings or 
feet, and are merely soft worm-like grubs. The males are 
active, and possess a single pair of large membranous wings. 
Unlike the Diptera, it is the posterior pair of wings which is 
