200 SYSTEMATIC ZOOLOGY 



serve to catch other aquatic larvae on which it feeds. The adult 

 dragon fly also is carnivorous and feeds on smaller insects. The 

 stone flies, so called because the larvae are abundant under stones 

 in brooks, have the posterior pair of wings much larger than the 

 anterior pair, and when at rest they are folded backward over 

 the abdomen. Most species are rather small, but some have 

 wings three centimeters in length. 



The termites, or white ants (Fig. 196), are also to be classified 

 here ; they may readily be distinguished from the true ants by 

 the light color of most of the individuals and the fact that 

 the abdomen is joined to the thorax by a broad band instead 

 of a narrow stalk. They are essentially tropical insects, though 

 some species are found in the United States. In structure 

 they are among the lowest winged insects, but their habits 

 of life are most interesting. They live in colonies in which 

 four kinds of individuals are represented : the light-colored 

 workers, which are males and females never attaining sexual 

 maturity, and wingless; the soldiers, very similar to the 

 workers, but having enormous heads and jaws ; the king and 

 queen, also wingless, but sexually mature and the parents of 

 the colony; and finally there are wingless complemental males 

 and females, which are sexually mature individuals which may 

 serve as substitutes for the true king and queen in founding a 

 colony. All the eggs are laid by the queen, which max - increase 

 in size from a centimeter or less to a length of from fifteen to 

 twenty centimeters. The king and queen are kept in a special 

 chamber, and fed by the workers ; as the eggs are laid the 

 workers carry them away to other chambers, where they develop 

 and where the larvae are fed. Eventuallv many of these larvae 

 develop into sexually mature winged individuals, black or dark 

 brown in color, which leave the nest, fly for some distance and 

 then alight on the ground, and their wings drop off. Most of 

 them are probably eaten by other animals, but whenever a pair 

 is found by a number of workers a new colony is started. The 

 nests built by the workers are often huge mounds as much as 

 three or four meters high, and are probably formed entirely 

 of undigested particles of wood which the insect has taken 

 into its digestive tract. These termites are great pests in many 

 parts of the tropics, where they eat out the inside of every 



