CHAPTER VII 

 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 developed and are used for a swarming 

 flight and then shed; second, the second reproductive caste, in which the 

 wing-buds remain short; the individuals are sexually mature but retain the 

 nymphal form; third, the worker caste; and fourth, the soldier caste. Ex- 

 cept 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 incomplete. 



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

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

 nized 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 composed, 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. In 

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

 little more in common than that both are social. 



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 neces- 

 sary 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 resemble those of the grasshoppers; but in the case 

 of the soldier caste the mandibles are very large. The members of the 

 winged sexual caste have compound eyes and a pair of ocelli. The 

 workers and soldiers of most termites are blind but in case of the march- 

 ing termite of Africa both the workers and soldiers possess eyes. 



The wings are long and narrow and when folded on the back of the 

 insect extend far beyond the end of the abdomen. The wings of the 

 sexual forms are shed after their flight. The shedding of the wings is 

 facilitated by the presence in each wing near its base of a curved trans- 

 verse suture, the humeral suture. 



* Isfiptera: isos (tow), equal; pier on (irrcpov), a wing. 

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