24 SOCIAL LIFE IN THE INSECT WORLD 



blind. What would be the use of sight underground ? 

 The eyes of the larvae leaving their burrows are black 

 and shining, and evidently capable of sight. When it 

 issues into the sunlight the future Cigale must find, often 

 at some distance from its burrow, a suitable twig from 

 which to hang during its metamorphosis, so that sight 

 is obviously of the greatest utility. The maturity of the 

 eyes, attained during the tiine of preparation before 

 deliverance, proves that tliQ larva, far from boring its 

 tunnel in haste, has spent a long time labouring at it. 



What else do we notice ? The blind, pale larva is far 

 more voluminous than in the mature state ; it is swollen 

 with liquid as though it had dropsy. Taken in the 

 fingers, a limpid serum oozes from the hinder part of 

 the body, which moistens the whole surface. Is this fluid, 

 evacuated by the intestine, a product of urinary secretion 

 — simply the contents of a stomach nourished entirely 

 upon sap ? I will not attempt to decide, but for 

 convenience will content myself with calling it urine. 



Well, this fountain of urine is the key to the enigma. 

 As it digs and advances the larva waters the powdery 

 debris and converts it into a paste, which is immediately 

 .ipplied to the walls by the pressure of the abdomen. 

 Aridity is followed by plasticity. The mud thus obtained 

 penetrates the interstices of the rough soil ; the more 

 liquid portion enters the substance of the soil by 

 infiltration ; the remainder becomes tightly packed and 

 fills up the inequalities of the walls. Thus the insect 

 obtains an empty tunnel, with no loose waste, as all the 

 loosened soil is utilised on the spot, converted into a 

 mortar which is more compact and homogeneous than 

 the soil through which the shaft is driven. 



