178 SPIDERS 



have dispersed. Sometimes she dies and then the spiderHngs 

 appear to feed on her body before they leave the nest. In this 

 species the Hfe cycle occupies two or more years. SpiderHngs 

 hatching in the summer reach maturity in the autumn of the 

 following year and lay their eggs when they are two years old. 

 They may live for another season or even longer. After hatching, a 

 period of some days may elapse before the spiderHngs scatter, 

 during which, as we have seen, they eat little or nothing. Bristowe 

 (1947) states that the mother Theridion sisyphium feeds her young 

 from her mouth. Whilst she hangs downwards, the babies jostle 

 one another to reach the drops of fluid she regurgitates for their 

 benefit, but this must be after the first ecdysis. For several days the 

 procedure continues and then for some weeks afterwards mother 

 and young feed simultaneously on the insects she catches. 



The number of moults necessary to attain maturity varies widely 

 in spiders. It has been shown that in most species, size is the deter- 

 mining factor: small spiders moult four or five times, those of 

 medium size seven or eight times while some of the Theraphisodae 

 may moult more than twenty times. Even within the same species 

 there is variation in the number of ecdyses. For example, in 

 Dolomedes plantarius the female may moult as few as nine or as 

 many as thirteen times, the number being correlated with size and 

 nourishment. 



Most spiders that inhabit the temperate zones live only one year, 

 but the more primitive species tend to live longer. In the majority 

 of species the life cycle varies from eight months to four years, and 

 the record for longevity is held by a Theraphosid, Eurypelma sp., 

 which lived for twenty years. The males mature in eight or nine 

 years, and usually die a few months later. 



The dispersal of young spiders of many species is achieved by 

 'ballooning', already mentioned. Those that survive the rigours of 

 these perilous journeys and land in a suitable environment begin a 

 life of toil and slaughter, of sacrifice and parental care which, for a 

 small proportion of fortunate individuals, may culminate in the 

 production of yet another batch of baby spiderHngs. 



