THE DIPTERA. 57 



120). In general appearance this larva resembles a small 

 green slug, with the skin much wrinkled, and bearing at its 

 extremity a short thick tube, which is probably the respi- 

 ratory apparatus, the four lunate holes situated at its apex 

 being no doubt the spiracles. These insects grow very 

 slowly, occupying several weeks to attain maturity. Their 

 mode of capturing the aphides is very curious, and is, 

 briefly, as follows : — The larva lies in the midst of a 

 number of aphides, and it occasionally happens that some 

 of them crawl over it. On feeling an aphis touch its back 

 the larva instantly darts out its long, pointed head and 

 strikes its prey with the apex, which is enveloped in a 

 quantity of very sticky mucus constantly ejected from the 

 mouth. On the aphis being thus captured the larva with- 

 draws its head into the hinder segments of its body 

 and devours all the juicy portions of the aphis, whose 

 dry skin is afterwards thrown aside. When full-grown it 

 slowly shrinks up and changes into the pupa shown at 

 Fig. 3b. In this state it is not protected by any kind 

 of cocoon, but lies amongst the refuse of the aphides, 

 near the stem of the plant. The fly emerges in a fort- 

 night or three weeks' time, and is very fond of hovering 

 over and sucking honey from the flowers, but the 

 females may be often noticed running about plants, 

 probably in search of a suitable place to oviposit. 1 For an 

 account of Scolobates varipes, a species parasitic on the 

 present insect, I refer to page 39. 



Family Syrphid.e. 



Eristalis cingulatus (Plate VII., fig. 2). 



This conspicuous insect occurs occasionally in glades in 

 the forest about January, but is by no means common. It 

 is very fond of the white rata flowers, where it may be 



1 Or lay eggs. 



