ii8 LIFE : OUTLINES OF GENERAL BIOLOGY 



workers, and a minority being males or drones. One of the pecu- 

 liarities ( f the termitary is that the workers are reproductively 

 arrested individuals of both sexes. 



(6) A second common feature is the prolongation of the mother's 

 life. In many in.sects reproduction is fatal, as is often seen in the 

 death of delicate butterflies soon after pairing and egg-laying. As 

 is well knowii, the Maytlies, which may have a larviil aquatic life 

 of several years, may have their winged, aerial, reproductive life 

 reduced to a single evening. In one species of these Ephemerids 

 the adult life is said to be condensed into a single hour! It is plain 

 enough that it would be difficult for the social habit to be established 

 under such conditions, for it implies a prolonged maternity and the 

 coe-xistence of numerous individuals of dilterent ages. In most 

 cases there must be nurses to look after the relays of larvie. 



It is a familiar, but none the less remarkable, fact that in the 



I'iG. 35. 



DiflcrtMit Forms of Termite. A, Vonng larva; H, adult worker; C, young 

 queen; D ami K, two types of soldier, .\fter Escherich. 



majority of insects the mother never sees her offspring. Under a 

 stone we may And a mother earwig with her miniature young ones 

 running about beside her, forming a family, but this is an unusual 

 scene. In most cases the mother has died before the young ones 

 emerge as winged insects, if not as larvie. Thus the usual brevity of 

 the mother's life among solitary insects precludes the social habit, 

 though there may be elaborate exhibitions of instinctive maternal 

 care in tlu^ provision of the nest with food for the emerging larva?. 

 The evolution of the social habit implies not only an increase in 

 maternal care, but an evasion of the Nemesis of death after repro- 

 duction. In starting a community the mother, as in the familiar 

 case of the Humble-lx-e, must be the first nurse. It is only later 

 that she can devolve her duties on her senior offspring. As Wheeler 

 insists, it was the lengthening out of the maternal stage that made 

 social life iK)ssible. S(x:ieties, among insects at least, are based not 

 only on maternal devotion, but on maternal vigour. Everything 

 depends on the mother being strong enough to be a nurse, and 

 strong enough to have repeated periods of egg-laying. 



