INSECTA 469 



thus contrasting with the Orthoptera. When unfolded, the wing 

 presents the appearance of a half wheel, the " spokes " radiating back- 

 wards from the anterior border, which is greatly strengthened. The 

 large posterior membranous portion corresponds to the anal wing 

 area of Orthoptera, that part corresponding to the anterior area of the 

 latter order having been greatly strengthened by the coalescence of 

 a number of longitudinal veins. The forceps are organs of defence 

 and offence. In Labidura they are used for seizing the small animals 

 on which this form lives. 



Order ISOPTERA (Termites or White ants) 



Social and polymorphic insects with biting mouth parts ; four-lobed 

 ligula; wings very similar, elongate and membranous, capable of 

 being broken off along a line at the base ; cerci short ; metamorphosis 

 slight. 



The animals of this order abound everywhere in the tropics. Like 

 the true ants they have types of individuals (castes), specialized for 

 the purpose of reproduction, labour and defence (Fig. 326). The 

 termite community usually contains a dealated royal pair^ the king 

 and queen, who are the founders of the colony, and also supple- 

 mentary reproductory individuals of two kinds: {a) winged, which 

 normally serve for the formation of new colonies, and {b) wingless, 

 which become capable of reproduction if occasion demands. There is 

 usually a vast number of sterile wingless individuals belonging 

 to two castes, the workers and soldiers. The termite nests may be 

 merely series of burrows in trees, dry timber or in the ground, or they 

 may be huge mounds made of earth cemented together with the saliva 

 of the termites. Those living in the ground excavate the soil of the 

 tropics, turning it over and enriching it just as earthworms do in 

 temperate regions. 



Their food consists chiefly of wood and other vegetable matter and 

 many species are extremely harmful, e.g. Neotermes, which damages 

 structural timbers, and Calotermes militarise which bores into and 

 does much harm to tea plants in Ceylon. 



The winged sexual forms in several colonies usually swarm at the 

 same time so enabling intercrossing between members of different 

 colonies to take place, and of the countless numbers a few individuals 

 escape the attacks of birds and ojther animals and alight and cast 

 their wings. 



A single pair forms a new colony first of all by making a small 

 burrow, the nuptial chamber. The first formed young are mostly 

 workers, and having themselves been tended to maturity by their 

 parents take over the nursing of the young. The queen becomes 



