vi] LARVAE AND THEIR ADAPTATIONS 67 



them alongside their eggs to furnish a food-supply 

 for the newly-hatched young. The social wasps and 

 many ants sting and kill flies and other insects, 

 which they break up so as to feed their grubs within 

 the nest. It is well known that the labour of tend- 

 ing the larvae in these insect societies is performed 

 for the most part not by the mother ('Queen') but 

 by the modified infertile females or 'workers.' Other 

 ants and the bees feed their grubs (fig. 18), also 

 sheltered in well-constructed nests, on honey elabo- 

 rated from nectar within their own digestive canals. 

 In all cases we see that the helplessness of the grub 

 is associated with some kind of parental care. 



From the Hymenoptera we may pass on to the 

 Diptera or Two-winged Flies, an order of which 

 the vast number of species and in many cases 

 the myriads of individuals force themselves on the 

 observer's notice. F. Brauer (1863) divided the 

 Diptera into two sub-orders 1 ; of the first of these 

 a Crane-fly or 'Daddy-long-legs' may be taken as 

 typical, of the second an ordinary House-fly or Blue- 

 bottle. All the larvae of the Diptera are legless, 

 those of the Crane-fly group have well-developed 

 hard heads, with biting mandibles, but in the House- 

 fly section the larva is of the degraded vermicidiform 



1 Known as the Orthorrhapha and the Cyclorrhapha ; these terms 

 are derived from the manner in which the larval or pupal cuticle splits, 

 as will be explained in the next chapter (p. 88). 



52 



