3-> 
out by Girschner (' Berliner Entomologische Zeitschrift,' Bd. xxxi. 
(1887), p. 156) " possess probably the finest eyes of all insects." After 
death, however, the colour of the eyes rapidly changes to a dull brown 
or brownish-black, until scarcely a trace of the markings remains.* 
In front of the eyes project conspicuously the three-jointed 
antennae, and below the head in all the British forms depends vertically 
the fleshy proboscis, or lower lip, which encloses the piercing mouth 
parts. The palpi, which lie one on each side of the proboscis, are 
swollen and fleshy, and differ in shape in the two sexes. The body 
is clothed with short hair and totally devoid of the large bristles 
known as macrochaitae. 
In the coloration as in the shape of the body horse-flies throughout 
the world show remarkably little variation, and the British species are 
consequently very similar in appearance to many of those belonging 
to the same genera found in Central Africa, India and elsewhere. 
Some shade of brown or black is the most frequent hue, though the 
abdomen is often lighter or exhibits lighter markings. The wings, 
which, when the insect is at rest, diverge at the tips or are some- 
what tectiform (sloping like the roof of a house), have in the case of 
HiEinatopota and Chrysops characteristic markings, which are well 
shown in the plates. 
Horse-flies maybe met with throughout the summer in fields, open 
spaces in woods, or by country roadsides. The edges of woods are 
favourite haunts of certain species, and when resting in such a place 
on a hot day one may frequently notice a Hcematopota or two or a 
specimen of one of the smaller species of Tab anus crawling with much 
deliberation over one's coat and making preliminary investigations with 
its proboscis. The females alone suck blood ; the males of certain 
species may occasionally be met with on flowers or sometimes hovering 
in the air. The species of Hcematopota and Chrysops, and the smaller 
species of Tabanus are remarkable for the quietness with which they 
alight on their victims, the sharp prick of the bite being often the 
first intimation of the presence of the fly. The larger species of 
Tabanus betray their approach by their deep hum. When once the 
operation of sucking blood has commenced, horse-flies, like other 
* In the plates to this work the eyes are shown as seen in dried specimens, from which 
the drawings had perforce to be prepared ; but so far as possible the natural colour and 
markings are indicated in the notes on each srjecies. 
