THE DIPTERA. 59 



state it delights to hover in the air, darting away with great 

 rapidity on the approach of any enemies. It also frequently 

 enters houses, where its presence is at once betrayed by a 

 peculiarly shrill noise made while flying. The sexes of this 

 insect differ chiefly in size, the female (Fig. i) being about 

 twice as large as her companion. 



Closely allied to this species are Helophilus ineptus, and 

 H. hochstetteri. The former is slightly smaller than H. 

 trilineatus and may be at once distinguished by its tessel- 

 lated orange-yellow and black abdomen. It is rather local, 

 but extremely abundant wherever found. The latter has 

 a superficial resemblance to some of the smaller blowflies 

 (Musca) y but may be readily known by its large brownish- 

 red scutellum. 1 It is the commonest of the genus and may 

 be found in great numbers throughout the summer amongst 

 veronica and other flowers. 



Family MUSCID.E. 

 Miltogramma mestor (?) (Plate VIL, fig. 5). 



A conspicuous species, 'found occasionally on forest-clad 

 hills round Wellington. The life-history is at present 

 unknown, but its larva is very possibly parasitic in some 

 large Lepidoptera. 



Family MUSCID^. 

 Nemorea nyctemerianus (Plate VIL, fig. 6). 



This little fly is seldom met with in the perfect state. 

 Its larva is parasitic on the caterpillar of Nyctemera annu- 

 lata? 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 



1 Scutellum : A horny plate situated on the mesonotum, usually 

 somewhat triangular in form. 



- For life-history of this insect see page 73. 



