52 SOCIAL LIFE IN THE INSECT WORLD 



them, in view of the importance of the operation. She 

 moves as little as possible, just so far as she must in order 

 to avoid running two adjacent egg-chambers into one. 

 The extent of each movement upwards is approximately 

 determined by the depth of the perforation. 



The apertures are arranged in a straight line when 

 their number is not very large. Why, indeed, should 

 the insect wander to right or to left upon a twig which 

 presents the same surface all over ? A lover of the 

 sun, she chooses that side of the twig which is most 

 exposed to it. So long as she feels the heat, her 

 supreme joy, upon her back, she will take good care 

 not to change the position which she finds so delight- 

 ful for another in which the sun would fall upon her 

 less directly. 



The process of depositing the eggs is a lengthy one 

 when it is carried out entirely on the same twig. 

 Counting ten minutes for each egg-chamber, the full 

 series of forty would represent a period of six or seven 

 hours. The sun will of course move through a con- 

 siderable distance before the Cigale can finish her 

 work. In such cases the series of apertures follows a 

 spiral curve. The insect turns round the stalk as the 

 sun turns. 



Very often as the Cigale is absorbed in her maternal 

 task a diminutive fly, also full of eggs, busily 

 exterminates the Cigale's eggs as fast as they are laid. 



This insect was known to Reaumur. In nearly all 

 the twigs examined he found its grub, the cause of a 

 misunderstanding at the beginning of his researches. 

 But he did not, could not see the audacious insect 

 at work. It is one of the Chalcididae, about one-fitth 



