ISOPTERA 65 



shown that both sexes are represented in this caste. The worker caste is 

 not always present. 



The soldiers. — ■ Associated with the workers, and resembling them in 

 color and in being wingless, there occur numerous representatives of 

 another caste, which can be recognized by the enormous size 

 of their heads and mandibles (Fig. 108); these are the sol- 

 diers. They are so named because it is believed that their 

 chief function is the protection of the colony; but they do 

 not seem to be very effective in this. Among the soldiers, 

 as among the workers, both sexes arc represented. 



The nest-building habits of these insects are remarkable. 

 In the tropics certain species build mound nests ten or 

 twelve feet or more in height. Other species build large 

 globular masses upon the trunks or branches of trees or upon 

 other objects. Owing to the delicacy of their cuticula and 

 the consequent danger of becoming shriveled if exposed, the FlG Io8 _ So] . 

 termites build covered ways from their nests to such places <jier of Retkuiitermes 

 as they wish to visit, if they are in exposed situations. These 

 exposed nests are composed chiefly of the excreted undigested wood upon 

 which the insects have fed. This is molded into the desired form and on 

 drying it becomes solid. 



The termites that live in the United States do not build exposed 

 nests; and, as the queens do not lose the power of movement, there is 

 no permanent royal cell, centrally located. Some of our species mine in 

 the earth, their nests being made under stones or other objects lying 

 on the ground; some burrow only in wood; and others that burrow in 

 the ground extend their nests into wood. 



In the warmer parts of this country and in the tropics termites are a 

 great pest for they destroy buildings by mining into the foundation 

 beams and into the timbers of the framework. Certain methods have 

 been devised for the construction of buildings in warm countries for the 

 purpose of making them termite-proof. 



Termites also destroy furniture and books, especially when the latter 

 are stored in basements. In - infesting anything composed of wood, they 

 eat out the interior, leaving a thin film on the outside. Thus a table may 

 appear to be sound, but crumble tc pieces beneath a slight weight, en- 

 trance having been made through the floor of the house and the legs of 

 the table. 



While termites infest chiefly dead wood, there are many records of 

 their infesting living plants, especially young orange and pecan trees in 

 the South. 



The common species of termite in the northeastern United States is 

 Reticulitermes flavipes. It often infests the wooden benches in greenhouses 

 and in some localities undermines buildings by eating out the inside of 

 the foundation timbers and then burrowing into the framework. 



