624 INSECTS AT HOME. 



The larva of the Syrplius is predacious, and feeds upon the 

 aphides ; so that every Syrphus that is seen in the garden 

 ought to be protected as an inestimable friend to the gardener. 

 In shape it very much resembles the Volucella larva whicli 

 has just been described, the g-rub being small and tapering at 

 the head, and wide and blunt at the tail. When the female 

 Syrphus is engaged in the great work of oviposition, she looks 

 out for the leaves or twigs which are most thickly beset with 

 aphides, and deposits an egg among them, never putting two 

 eggs near each other. As soon as it is hatched, the young 

 Syrphus larva finds itself in the midst of its food, and straight- 

 way takes advantage of the position in which it is placed. 

 Clinging to the leaf with the projections on its under surface, 

 the larva stretches out the fore part of the body, and, with a 

 curious apparatus belonging to its mouth, seizes on an aphis. It 

 then pulls the aphis from its hold on the leaf or twig, and holds 

 it aloft, so that the struggles of its prey are quite useless, and 

 in this position sucks the juices. A very few minutes suffice for 

 this operation, and it then throws away the emptied skin of the 

 unfortunate aphis, and waits until another comes in its way. 



When full-fed, the Syrphus larva fixes its tail very firmly to 

 the plant on wliich it has been living, attaching it by means 

 of a sort of glue or cement. The whole of the body then 

 contracts, and the pupa is developed within the larval skin, 

 which acts tlie part of a cocoon. It is a curious fact that 

 when this change takes place, the creature exactly reverses its 

 shape, the thick, blunt tail being contracted nearly into a 

 point, while the slender, attenuated fore part of the body 

 becomes thick and blunt. Before many days have elapsed, 

 the fly is fully developed, pushes strongly against the end of 

 its habitation, forces off the end with its head, and emerges 

 upon the world. 



Another species of these insects, Syrphus or Sccava pyvastri, 

 is shown on Woodcut LXXIII. Fig. 1. This fine insect is 

 blackish-blue, on which is a whitish-grey down. The thorax 

 is very shining, and on each side of the abdomen are three 

 short bands, varying from pure white to golden yellow. In 

 some few species the bands are absent. The larva may be 

 found feeding on the aphides of the rose-tree. 



