256 THE BIOLOGY OF INSECTS 



wings appear. The soldier termites also remain wingless, 

 and are in that respect undeveloped and youthful in their 

 character ; but their heads are highly modified, large with 

 firm, brown capsule, either bearing extremely prominent 

 trenchant mandibles or prolonged into a snout-like process 

 with a repellant gland opening at its tip. They are the 

 defenders of the termite society. It is believed that from 

 eggs of the third-form females, fertile insects like themselves 

 as well as workers and soldiers can be developed. The 

 second-form fertile termites may be parents of members 

 of their own and of the three " lower " castes. Only the 

 kings and queens can give rise to all the varied forms of 

 their kind. When exceptionally a worker or a soldier 

 becomes fertile, it can reproduce its own caste only. 



The fertile female termites, in whose bodies numerous 

 eggs are developing, tend to become swollen in the abdominal 

 region, tracts of pale cuticle showing between the darker 

 sclerites, as the integument is stretched. In most " queens " 

 (Fig. 64, e) this process is carried to an extreme degree, the 

 swollen abdomen becoming seven or eight times as long as 

 the rest of the body, with its area almost entirely composed 

 of tense whitish cuticle. Thus, while a pair of termites 

 starting a new nest are of the same size, it comes to pass 

 that in some species the " physogastric " queen is four 

 times as long and a hundred times as bulky as her mate, 

 and perhaps fifteen times as long and three thousand times 

 as bulky as her worker offspring. K. Escherich, in his 

 excellent account (1909) of the termites, reckons that a 

 queen of the tropical African Termes hellicosus lays about 

 thirty thousand eggs a day, a rate of reproduction which 

 would work out to ten million eggs a year, and to a hundred 

 million eggs in the average ten-year life of one of these 

 insects. He concludes, therefore, that such termite queens 

 must be regarded as the most fruitful females in the whole 

 animal kingdom. 



The staple food of termites is wood, and the damage 

 which these insects do to timber structures is too well 

 known to dwellers in tropical and sub-tropical regions. The 



