Descriptions of British Diptera. 161 
They probably derive their nourishment from the saccharine juices 
which frequently exude from the leaves of plants. We are 
still imperfectly acquainted with their larvae. One described by 
Reaumur was found to live in cow-dung. It was of an oblong fi- 
gure, narrowing to a point anteriorly, and furnished with two hooks 
at the head, which is of a scaly texture. Its metamorphosis took 
place within the skin of the larva, and the fly made its exit by push- 
ing outwards the portion that covered the head and first segment. * 
1. SARGUS CUPRARIUS, (s.J 
Musca cupraria, Linn. Fabr Nemotelus cuprarius, De Geer, vi. 200, tab. 
12, fig. 4. Sargus cuprarius, Fabr. Syst. Ant. 
Forehead bluish-black, shining and pubescent, narrow in the 
males, somewhat wider in the females ; antennae brown, with a small 
white spot over the base of each ; eyes brassy green during life, with 
a horizontal purple band a little above the middle, the superior space 
more or less inclining to that colour, particularly behind ; thorax 
shining golden-green, pubescent, the sides blue-black ; halteres pale 
yellow, or whitish ; wings vitreous at the base, more or less clouded 
with brown in the middle, especially from the anterior margin across 
the discoidal cell ; abdomen cupreous, shining and pubescent, the 
hinder parts more or less glossed with violet, the whole being of the 
latter colour in the female except at the base ; the under side shin- 
ing black inclining to blue ; legs black, the tip of the thigh, base 
of the tibiae, and some of the joints of the tarsi inclining to reddish- 
yellow. 4-5 lines. 
This beautiful insect is found from May till August, and seems 
to be not uncommon in most parts of the country. It frequents gar- 
dens, shrubberies, and sheltered lanes, and is not observed much on 
the wing, but reposing on the foliage, as if enjoying the sunshine. 
It has been noticed in many parts of Scotland, and it is sometimes 
rather plentiful in the Botanic Garden of Edinburgh, and other 
places near the Scottish metropolis. The female is always much 
more plentiful than the male. " I found this splendid insect 
in abundance on the borders of a wood near Dover, on the 14th of 
July, and took a female in Scotland the same month." Curtis, .#. E. 
vii. fol. 305. " Near London," Stephens. " Dunkeld and Dum- 
* Reaumur, Memoir es pour VHistoire des Insectes, iv. 348 It is difficult to 
determine from Iris rude figure, (pi. 22, fig. 7-8,) what species of Sargus origi- 
nated from this larva ; it cannot be S. cuprarius, as De Geer and Latreille sup- 
pose, (Regne Animal, v. p. 487,) for the belly and legs are described as being 
pale yellow. Meigen conjectures that it i-, the species which has since been 
named S. Reaumuri. 
NO. II. L 
