CHAPTER X 



ORDER ISOPTERA* 



The Termites or White-Ants 



The members of this order are social insects, living in colonies like 

 ants. Each species consists of several distinct castes, the number of 

 which differs in different species. Each caste includes both male and 

 female individuals. In most species there are four castes as follows: 

 first, the first reproductive caste, in which the wings become fully de- 

 veloped and are used for a swarming flight and then shed; second, the 

 second reproductive caste, in which the wing-buds remain short; the 

 members of this caste are neoteinic, becoming sexually mature while 

 retaining the nymphal form of the body; third, the worker caste; and 

 fourth, the soldier caste. Except in a single Australian genus, the two 

 pairs of wings are similar in form and in the more general features of 

 their venation; they are long and narrow, and are laid flat on the back 

 when not in use. The abdomen is broadly joined to the thorax; the 

 mouth-parts are formed for chewing; the metamorphosis is gradual. 



The tennites or white-ants are chiefly tropical insects; but some 

 species live in the temperate zones. These insects can be easily- 

 recognized by the fact that they live in ant-like colonies, by the pale 

 color of the greater number of individuals of which a colony is com- 

 posed, and by the form of the abdomen, which is broadly joined to 

 the thorax instead of being pedunculate as in ants. 



The termites are commonly called white-ants on account of their 

 color and of a resemblance in form and habits to the true ants. 

 These resemblances, however, are only very general. In structure 

 the termites and ants are widely separated. In habits there is little 

 more in common than that both are social, and the fact that in each 

 the function of reproduction is restricted to a few individuals, while 

 the greater nimiber differ in form from the sexually perfect males and 

 females, and are especially adapted to the performance of the labors 

 and defense of the colony. 



The cuticula of termites is delicate even in adults; the mature 

 winged forms can withstand exposure to dry air for a limited period, 

 as is necessary during their swarming flight; but other members of 

 a colony quickly become shriveled and die if exposed. It is for this 

 reason that they build tubes constructed of earth and excrement for 

 passage-ways, and only rarely appear in the open, and then merely 

 for a brief period. 



The mouth-parts, which are fitted for chewing, are quite general- 

 ized, resembling somewhat those of the Orthoptera; but in the case 

 of the soldier caste the mandibles are very large and vary greatly in 

 form in the different species. 



*Is6ptera: isos Q-ffos), equal; pteron {irrepbv), a wing. 



(273) 



