This little fly is seldom met with in the perfect state. Its larva is parasitic on the caterpillar of _Nyctemera annulata_[13], the eggs being deposited on the moth larva at an early age. The caterpillar grows and eats in the ordinary way, until it has assumed the chrysalis state, when the {60}maggot eats its way out and changes into a dark-brown pupa. In this condition the parasite is protected by the web which was previously constructed by the unfortunate caterpillar for its own use. The perfect fly appears in about six weeks' time, its great agility and large white scales rendering it very conspicuous. Family MUSCIDÆ. _Eurigaster marginatus_ (Plate VII., fig. 7). Another parasitic species, its larva inhabiting the caterpillars of various noctuæ which it destroys just before they change into the chrysalis state. The pupa of the parasite lies in a small oval cell constructed in the earth by its larva. A variable number of these maggots are found associated in one host, the smaller caterpillars only harbouring a single individual, while a large larva will frequently contain three or four. This species has been bred from the following Lepidoptera: _Mamestra composita_, _M. ustistriga_ and _M. mutans_. It also occurs in the curious _Oeceticus omnivorus_, being found in the cocoons of that moth in numbers varying from two to eleven, or even more, and it is especially interesting, as it is in turn destroyed by a small species of _Pteromalus_ already noticed among the Hymenoptera (page 37). The perfect insect occurs occasionally on flowers throughout the summer. Family MUSCIDÆ. _Calliphora quadrimaculata_ (Plate VII., fig. 9). This is the large blue-bottle fly of New Zealand and is found everywhere in great abundance. Its larva feeds on decaying flesh and is of a dirty yellow colour, measuring, when full-grown, about seven lines in length. The pupa is buried at a considerable depth in the ground, the {61}larva having descended before changing. The duration of this, and in fact of all the stages of the insect, depends entirely upon the temperature, but the females invariably deposit eggs, even during the hottest weather, and are never ovo-viviparous like the next species, and several others of the genus. Family MUSCIDÆ. _Sarcophaga læmica_ (Plate VII., fig. 10).