Miller. — Bionomic Observations on New Zealand Diptera. 229 



Fam. DoLicHOPODiD^. 

 The males of this family bear sexual ornamentations on the legs, head, 

 the third joint of the antennae, as well as on other parts. The species 

 of this division are small. 



Psilopus mobilus. 



Very cjmmou in the bush at Taieri Mouth during January (1908). 

 These flies were found, basking in the sun, on tree-trunks. I captured 

 only two at Murdering Beach in January (1909), and these were resting 

 on rushes which grew in a swamp behind the sandhills. 



Series CYCLOEKHAPHA ASCHIZA. 

 Fam. Syrphid^ (Hover-flies). 



The members of this family are both large and small, and are beauti- 

 fully coloured with yellow and green. They are usually found hovering over 

 flowers in the sun, and can be recognised by their mode of flight alone, 

 which is described thus by Kirby : " They hover motionless in the air, 

 and, if alarmed, dart off with a rapid motion that the eye cannot follow, 

 and hover again as soon as they stay their course."* The larvae are 

 beneficial to gardeners, as they destroy large numbers of injurious insects. 



Eristalis tenax (introduced). 



Abundant everywhere from February to March ; also found — but in 

 decreasing numbers — in April and May. This species is fomid hovering 

 abou# flowers in the sun. When it alights, the abdomen may often be seen 

 moving up and down, and the wings are held in such a position as to expose 

 the abdomen. I observed a specimen feeding on the pollen of a dande- 

 lion : the fly took hold of the stamen of a flower with its proboscis — which 

 appears to be bifid at the distal extremity — and passed it once or twice 

 up and down the stamen in order to rub of! the pollen. After this opera- 

 tion had been indulged in two or three times, the fly held out its proboscis 

 at full length, and moved the bifid portion as if it were in the act of tasting. 

 Anothe? specimen I observed to rest on the broken end of a holly-twig, 

 by alighting so that the sharp edge of the broken twig came between the 

 bases of the fore and middle legs ; the fly steadied itself with the posterior 

 tarsi pressed against the sides of the twig, while it cleaned its fore tarsi 

 and proboscis ; the middle legs meanwhile were outstretched. This speci- 

 men remained thus for about four minutes. 



Helophilus trilineatus. (Plate XXIX, fig. 5.) 



Not very common. I captured one specimen at Taieri Mouth in Janu- 

 ary (1908) as it alighted on a blade of grass in the sun. At Roslyn, during 

 February of the same year, two were obtained resting on a marigold-flower 

 exposed to the sun. 



Helophilus antipodus. 



Found at Eoslyn, November (1908). I captured this species amongst 

 some long grass in the sun, the day being very warm. A large number 

 were observed hovering over a stream on Mount Cargill during February 



* I have lately observed a distinct difference between the flight of S. novce-zealandice 

 and that of M. fasciatum : the movement of the former being jerky contrasted with 

 the gliding motion of the latter. 



