TABANIDAE. 



In the Japanese Islands, as elsewhere, the horse-flies or 

 Tabanids, owing to the size of many of the species, are the most 

 formidable in appearance, of all the blood-sucking insects, Indeed 

 a large female of Tabauus chrysurus, Loew, measuring over an inch in 

 length, with a wing expense oi nearly two inches, is exceeded in size 

 by 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 Japanese insect. 



The horse-flies, which are world-wide in their distribution, are 

 also among the largest of ail families of Diptera, the total number of 

 species described at the end of the year 191 5 being no less than 2200. 

 In the Japanese Islands there are fifty-six recognized species belonging 

 to the genera Haematopota, Tlierioptectes, Atylotus, Tabanus, Isshikia y 

 Chrysops, Corizoneura and Silvins ; I believe we should find more 

 species if they were carfully collected through the Islands. 



In appearance the Tabanidae are mainly bulky-bodied flies, with 

 a large head (except in the genus Corizoneura), which is convex in 

 front and concave or flattened behind. The head is almost wholly 

 composed of the eyes: in the male the latter meet together above, 

 but in the female they are separated. Most of the males have 



usually 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 Chrysops and Haematopota, which 

 posses probably the finest eyes of all insects. After death, however, 

 the colour of the eyes rather rapidly changes to a dull brown or 



