125 



PROGRESS IN THE STUDY OF VERRUGA TRANSMISSION BY 



BLOODSUCKERS. 



By Charles H. T. Townsend, 



Director of Entomological Stations for Pern. 



(Plates X— XII.) 



Referring to the papers by the writer in the Inca Chronicle (March 1913), and 

 the Journal of Economic Entomology (April 1913), it is time to make the 

 announcement that the experiments under way during May and June 1913, have 

 so far been entirely negative as to the transmission of verruga by ticks or mites. 

 What were at first taken for young stages of a tick, and referred doubtfully to 

 Ornithodoros, have proved to be young and adults of one or two species of 

 Gamasid mites near the genus Leiognathus. These were found in abundance, 

 engorged and unengorged, on all vizcachas (Lagidium pernarum, Meyer) 

 examined from over 12,000 feet altitude down to well within the known verruga 

 zone of the Rimac valley. On the possibility that these mites may infect through 

 being swallowed, as in the case of Haemogregarina (Hepatozoon) transmitted by 

 Laelaps, a large number of the mites were fed to monkey, rabbit, guinea-pig, dog 

 and fowl. A rabbit and a guinea-pig were exposed to the bites of the mites for 

 113 and 125 hours respectively at a stretch. Injections of the mites macerated 

 in an artificial serum were given subcutaneousiy to monkey, rabbit, guinea-pig 

 and dog. The feeding and biting experiments date from the middle of May 

 1913, and the injection from the first of June. The mites used represented 

 nymph and adult stages and all ages since partaking of a blood-meal, some being 

 completely engorged, some partially engorged, and many wholly free from traces 

 of blood. Temperatures were taken constantly but no notable rises were 

 detected. Blood-smears from the treated animals stained with Giemsa showed 

 nothing abnormal. 



The only true tick found on the vizcacha was Ixodes lagotis, Gervais. It was 

 secured in the larva, nymph and adult stages. The larva and nymph possess the 

 peculiar inner spine to the first palpal joint, which is lost in the adult, as described 

 by Nuttall and Warburton for /. angustus, Neumann, to which the species is 

 evidently allied. Thus this species was originally referred to the right genus, 

 though known to Gervais only in the nymph, and is not a Haemaphysalis, as had 

 been supposed by Neumann, Lahille and others. It was not experimented with, 

 partly from lack of sufficient material, and also owing to the fact that, on 

 account of its wide range southward into Chile, it does not offer much promise of 

 being a verruga transmitter. 



The native rats of the higher Andean region show abundant infestation with 

 an Ixodes sp., but no Argasids have yet been found on them. Various birds are 

 also infested with Ixodes spp., one of them appearing allied to I. auritulus, 

 Neumann. Larvae of Argasid ticks, probably Argas spp., have been taken 

 from goatsuckers and a ground-owl {Athene sp.) in the lower part of the verruga 

 zone. An Ornithodoros sp., of nocturnal habit, distinct from both O. talaje, 

 G. M., and turicata, Duges, but more allied to the latter, occurs in all stages in 



