104 



HARDWl CKE ' S S CIENCE- G OSS IP. 



Xylophagus afer, F., is illustrated in Walker's 

 "Diptera,"i. PI. i., Fig. lo. 



14. TabanidiV. 



These flies are the largest British diptera, about 

 twenty species being indigenous ; popularly known as 

 gad-flies. The old Roman and Greek writers allude 

 to flies which were evidently species of this group. 



The 9 attack cattle, and alighting on the back 

 of the animal, draw blood by means of the long, 

 powerful proboscis. The male is comparatively 

 harmless, and feeds on the juices of flowers. They 

 pair in the air, and frequent woods and pastures, 

 their abundance often making certain roads im- 

 passable, as some species readily attack man. The 

 Rev. J. G. Wood recommends smearing the face, 



Fig- Ti-—Siratiomyia, Geoff. 



Fig. T^.—Dioctria, Mg. 



Fig. •js.—Thereva, Latr. 



neck, and hands with parafiin as a preventive against 

 their attacks. 



Their flight is very rapid, with a loud hum, and 

 they occur most abundantly in the New Forest. 



Two sub-families are recognised, the venation 

 being the same in both. 



No ocelli ; posterior tibiae unarmed ( Taianinar). 

 Antennae seven-jointed. 



Eyes bare : Tabanuj, L. 

 Eyes pubescent. 



Ocellar tubercle on vertex : TheriopUctes, Zell. 

 No ocellar tubercle : Atylotus, Os. Sac. 

 Antennae six-jointed : Hccmatopota, Mg. 

 Ocelli present, three [Pangonince) . 

 Posterior tibiae with small spine at the tip : Chrysops, Mg. 



Tabatiince. — Hamatopota pluvialis, L., is a greyish- 

 black fly marked with lighter bands ; the wings are 

 mottled grey, with light curved lines and circles ; 

 long 8 mm. ; often very troublesome to pedestrians. 



Tabanns suddicus, Zell. This species, the largest 

 British fly, is usually mistaken for T. bovinus, L. (a 

 much less common species in Britain). It is of a 

 tawny brown colour, the abdomen being marked 



with darker bands ; the wings are pale grey with 

 tawny veins ; legs tawny with black tarsi tips ; long 

 20 mm. 



T. bromius, L., a smaller species of a grey colour, 

 with pale grey wings and blackish-grey legs, is also 

 common ; long 13 mm. 



PangonincE. — Chrysops, Mg., is a black and yellow 

 fly, with light wings, marked deeply with brown in 

 the cf, those of the q being almost entirely brown; 

 the sexes also diff'ering in the form of the abdominal 

 markings ; long 9 mm. ; chiefly from the south coast. 

 Brauer in 1880 published a splendid monograph of 

 the European species of Tabanus, his chief specific 

 characteristics being the number, size, and direction 

 of the bands on the eyes (coloured during life), the 

 shape of the antennse, and general form of the frontal 

 stripe. 



1 5- Lep tides. 



Six genera and about twenty species are British, 

 though several others have been wrongly introduced 

 as such. Long-bodied, large-winged, long-legged 



Fig. •;(>.— Asiltts, L. 



Fig. 77. — Scenopinus, Latr. 



flies of delicate structure, found in woods and shady 

 localities, the larva living in decaying wood or in the 

 earth. 



Some species inhabit marshes and ditches. The 

 metamorphoses of several species are known, 

 Degeer saying they take three years to reach 

 maturity. De Romand states that the larva has 

 been known to fast for six months. 



The venation of all the genera is similar, but the 

 structure of the antennae varies. 



The three principal genera are thus separated : — 



Anal cell open : Leptis, F. 

 Anal cell closed. 



Wings uniformly clear: Chryiopila, Meq. 



Wings spotted with brown: Atherix, Mg. 



L'ptis tringaria, L., is a large, tawny, long-bodied 

 fly, with long, tawny legs, and wings tinged with 

 tawny brown ; abdomen tawny, with a dorsal row of 

 black spots ; long 9-10 mm. 



L. scolopacea, L., an allied species, differs in having 

 wings marked extensively with brown ; both common. 



