OF VERRUGA TRANSMISSION BY BLOODSUCKERS. 127 



canyon. With a couple of candles set in front of a glass window in the railway 

 station, he caught something over a hundred small gnats between 6.30 and 

 9.30 pm. He was told that these gnats suck blood and are called titira by the 

 natives. None of them attacked him so far as he was aware. Those caught 

 appeared to be Ceratopogoninae largely, and on showing them the next 

 morning to a native ranchero the latter stated that the true titira possesses white 

 wings and breeds in the hills. This description immediately suggested 

 Phlebotomies, but further search seemed to indicate nothing as to the presence of 

 these flies in the region. Verrugas canyon itself, which is considered to be the 

 principal focus of the disease, was explored for five hours by the writer on 25th 

 ♦June, and previously for three hours on 16th April, but without finding any- 

 thing there further than strictly day-biting insects — Simulium and Tabanids. 

 On the first occasion the bed and sides of the canyon had been well dragged with 

 white flannel cloths by the writer and his assistant, Mr. E. W. Rust, for some 

 considerable distance above the famous Verrugas Bridge, but without finding a 

 single tick of any description. At the mouth of the canyon and at San 

 Bartolome, sleeping quarters and bedding had been carefully examined in April 

 without finding anything other than Culicids and fleas, though at that date a 

 child, inmate of one of these apartments, was seen in the characteristic fever 

 stage of the disease, proved by a magnificent nodular eruption of two weeks 

 standing, when seen again on 25th June. On the latter date an Italian, who had 

 been breaking rock for some weeks in camp between Verrugas canyon and San 

 Bartolome, was brought into the station building in characteristic condition of 

 anaemia aud fever, evidently verruga, as he acknowledged that he had been much 

 bitten by titira in the evenings while in camp. 



A detailed microscopic study of the gnat material secured, revealed, as more 

 or less pertinent to the investigation, some 40 specimens of a Ceratopogon sp. 

 which occurs also at Chosica ; about 40 or more of what is probably an 

 Orthocladius sp., also occuring at Chosica ; a dozen or so of a Tanytarsus sp. ; 

 and lastly, 2 specimens of a Phlebotomus sp., which had been taken with the rest 

 without suspecting their identity ! The Ceratopogon and Tanytarsus appear to 

 possess mouth-parts adapted for bloodsucking, especially the former, but none of 

 them was engorged. A balsam mount of the mouth-parts of the Orthocladius 

 indicates the bare possibility of this form sucking blood also. The Phlebotomus 

 admits of no question in this regard. The two specimens of the latter, it should 

 be noted, lacked the legs and had evidently been lying dead for some time on the 

 window frame, for all gnats seen, dead or alive, were carefully removed from the 

 window during the collecting. All information obtainable in the district indicated 

 that the titira were more abundant at night in the vicinity of Verrugas canyon 

 than at San Bartolome at this season. The term titi is apparently used inter- 

 changeably with titira for all the extra-culicid biting gnats that appear at night 

 in the verruga zone, but the true titira appears to be the Phlebotomus sp. 

 without doubt, from its distinctively adapted blood-letting mouth-parts and 

 unquestioned blood-sucking habit. Moreover, it does not occur at Chosica, 

 while the above-mentioned Cerotorogoninae do occur there. 



Here at last is probably the true explanation of the observed facts, frequently 

 dwelt upon by Dr. Ernesto Odriozola, to the effect that verruga localities are 

 31343 C 



