456 THE WONDER OF LIFE 



appendage. This quaint form moults and there comes 

 forth a migratory larva, no bigger than a flea, which hangs 

 by its tail for an hour or a day at the end of a thread, waving 

 its antennae and bending its legs. It falls to the ground 

 and seeks for a spot of pervious soil into which to burrow. 

 It becomes a deep burrower and taps the roots of plants, 

 probably remaining, Fabre thinks, for four years under- 

 ground. We venture to quote from his Social Life in the 

 Insect World, the summing up of this extraordinary life- 

 history. 



' Four years of hard labour underground, and a month 

 of feasting in the sun ; such is the life of the Cigale. Do 

 not let us again reproach the adult insect with his trium- 

 phant delirium. For four years, in the darkness, he has 

 worn a dirty parchment overall ; for four years he has mined 

 the soil with his talons, and now the mud-stained sapper 

 is suddenly clad in the finest raiment, and provided with 

 wings that rival the bird's ; moreover, he is drunken with 

 heat and flooded with light, the supreme terrestrial joy. 

 His cymbals will never suffice to celebrate such felicity, 

 so well earned although so ephemeral '. 



The common house-fly (Musca domestica ) can pass through 

 the whole of its intricate development — ^with three larval 

 stages and a pupal stage — ^in eight days, if the temperature 

 is steady and high (35° C), but the same process may be 

 lengthened out over several weeks. According to Hewitt, 

 the flies become sexually mature in 10-14 days after their 

 emergence from the pupa-stage. Each fly lays from 120-150 

 eggs in a single batch, and may lay as many as six batches 

 during its short hfe. Except in warm stables and thehke, 

 where reproduction may go on practically without stopping, 

 the breeding period is usually from June to October. 



