3i 
Family 
tabanim;. 
(Horse-flies, or Breeze-flies, Dun-flies, Clegs and Stouts, frequently 
called Gad-flies ; in Kent the species of Hcematopota are locally known 
as Br imps*) 
In the British Islands, as elsewhere, the horse-flies, owing to the 
size of many of the species, are the most formidable in appearance of all 
the blood-sucking Diptera. Indeed a large female of Tabanus sudeticus, 
Zlr. (Plate 2o), measuring nearly an inch in length, with a wing 
expanse of over an inch and three-quarters, is exceeded in size by 
but very few exotic species of this family, and frequently excites the 
surprise of those who are not entomologists, when they learn that it 
is really a British insect. The horse-flies, which are world-wide in 
their distribution, are also among the largest of all families of Diptera, 
the total number of species described at the end of the year 1904 
being no less than 1,560. In the British Islands there are twenty-two 
recognised species belonging to the genera Hcematopota, Therioplectes, 
Atylotus, Tabanus and Chiysops. Of Pangonia (which, as regards 
number of species, is the second of the principal genera of this family, 
and is remarkable for the length of the proboscis, which, in some 
species, greatly exceeds that of the body) there is no British 
representative. 
In appearance the Tabanidre are bulky-bodied flies, with a large 
head, which is convex in front and concave or flattened behind. In 
the male the head is almost wholly composed of the eyes, which meet 
together above in that sex but are separated in the female. The males 
have an area in the upper portion of the eyes, varying in extent 
according to the species, composed of larger facets than those below. 
In life the eyes usually exhibit golden green or purple markings, which 
are of value for the identification of species, and are especially brilliant 
in the case of the females of Clirysops and Hcematopota, which, as pointed 
* Apud F. V. Theobald, ' Second Report on Economic Zoology ' (British Museum 
(Natural History). London, 1904), p. 15. 
