238 F. W. EDWARDS. 



dark stripes on tlie thorax of the female vary in width and distinctness, being 

 hardly distinguishable in very dark specimens ; the legs are much darker in some 

 specimens than in others. 



Examples from the Mediterranean region (e.^., those recorded in my previous paper 

 from Fez) differ in the paler colour of the pubescence of the thorax in the female. 

 Some pupae of this form collected by Capt. J. Waterston in Macedonia difier from the 

 British forms in having the six minor branches of the respiratory organs longer, more 

 slender, and closer together at the base. The larvae are alike. A single half- 

 developed female pupa of this form has recently been given me by Mr. M. E. Mosely, 

 who took it in company with normal pupae in the River Test, Hants., ix.l920 

 (see fig. 6,c). 



Blood-sucking. — ^Ample confirmation has been obtained of the statement that this 

 species normally feeds in horses' ears, and it would seem that it is the only blood- 

 sucking fiy in Britain which does so ; its activities must therefore be only too well 

 known to agriculturists. Numbers of females were taken from ears of barge-horses 

 on the canal near Uxbridge, 21.viii.l6, no other species being seen. On 5th April 

 1918 (as well as on other occasions) many were found in ears of farm horses at Letch- 

 worth, from 30 to 40 in each ear, and though all were carefully examined no other 

 species was found. Some of these specimens were so gorged that the blood was 

 oozing from the end of the abdomen ; contrary to Pomeroy's observation regarding 

 S. venustum in America, they were not at all readily disturbed. On another occasion 

 they were found to be much more numerous still, covering the inside of the ear Hke 

 velvet, with their bodies closely packed, at right angles to the surface of the ear, 

 and holding on only by their mouth-parts and front legs. Again at Digswell, Herts., 

 9.vii.l9, swarms of females of this species (and no other) were found flying round 

 horses' ears ; the animals were much troubled by them and endeavoured to escape 

 by standing in the river with their heads under the arch of a bridge, against which 

 they could flick their ears. I have never found this species biting any other part of 

 3i, horse. 



On one occasion (Letch worth, 19.x. 17) a few specimens were found in calves' ears, 

 while at the same time there were numerous S. ornatum 5 on the bellies of the 

 animals. I think, however, there is no doubt that the horse is the main host, as I 

 have several times searched for them in vain in the ears of cows. 



Mr. A. H. Hamm has supplied me with one or two additional records of the species 

 biting the human subject ; I have not experienced the bite myself, though a few of 

 the insects not infrequently fly round one. It is of some interest to note that, as 

 might be anticipated, they fly round the top of the head and often settle on a person's 

 hat. 



References. — The remarkable pupa of S. equinum has been described and figured by 

 Vogler (Mitt. Schweiz. Ent. Ges. vii, p. 278, 1886), who did not however recognise 

 the species he was describing. There are two other described pupae which bear 

 an approximate resemblance to S. equinum. These are S. botulibranchium, Lutz, 

 from South America and S. damnosum, Theo., from tropical Africa — the latter 

 recently described by Pomeroy (Ann. Mag. Nat. Hist. (9) v, p. 80, 1920). The adult 

 of Lutz's species is unknown ; that of S. damnosum has a much greater resemblance 



