211 



HowLETT (F. M.). The Natural Host of Phlehotomus minutus. — 

 Indian Journal of Medical Research, Calcvfia, i, no. 1, July 

 1913, pp. 34-38, 1 map, 1 pi. 



The author says that a study of the habits of Phlehotonius 

 mimitus, the commonest sand-ily in liehar, gives the impression 

 that it is not strictly a domestic species and that it must either 

 be able to dispense with blood altogether or must have some other 

 source of supply than man. It breeds nearly all the year round 

 (at Pusa), but bites human beings only in the summer, and 

 apparently a meal of blood is necessary to secure the fertility of 

 the eggs. The author states that he is now fully convinced that 

 at Pusa a common gecko will prove to be the natural host of 

 Phlehotomus minutus, and that the association with man may be 

 of a secondary nature. The evidence with regard to the connection 

 between the sand-fly and lizards is briefly as follows: — The dis- 

 tribution of P. minutus is not yet fully known but the typical 

 minutus and its variety- africanus are recorded from India, the 

 Mediterranean area, the Gold Coast, North and Soutli Nigeria, 

 the Sudan, North-East Ehodesia and Nyasaland (Newstead). A 

 map is given showing the distribution of Geckonidae throughout 

 the world and the author points out that this more or less coincides 

 with the distribution of P. minutus. The natural habitat of the 

 fly at Pusa is practically confined to places where there are stones, 

 bricks or tiles and tree-trunks. The attempt to collect them 

 elsewhere is profitless and this habitat more or less precisely 

 coincides with that of the common Gecko. There is a note- 

 worthy exception to this general statement in that P. minutus 

 has been found in some numbers in the nests of termites by 

 T. Bainbrigge Fletcher in the neighbourhood of Coimbatore and 

 by the author at Amritsar. Careful search has hitherto failed tO' 

 reveal larvae in the cracks inhabited by lizards in the walls of 

 bungalows, but the fact that the female sand-fly will not oviposit 

 in a dry place is sufficient explanation, as all these cracks are 

 dry and sheltered. 



It is the adult female Phlehotonius which is most closely asso- 

 ciated with the gecko. In the evening both come to light, the 

 gecko in search of insects. In the daytime the female flies are 

 often to be seen close to crevices in which geckos are hiding and 

 sometimes enter them, the males generally remaining outside. 

 'In a bungalow in which P. minutus is abundant, careful examina- 

 tion of the lizards on the wall, at almost any time of day or 

 evening, may reveal that perhaps every other lizard has a sand-fly 

 perched on its back and sucking its blood, an operation which 

 takes a long time, often an hour or more. The lizard rarely 

 makes any effort to free itself of the fly, and has never been seen 

 to eat one, although geckos are well known as voracious in« 

 sectivores. The fly will only bite man in the hot months in the 

 late evening or very early morning, and it is extremely difficult 

 to persuade them to bite the hand or arm in the laboratory during 

 the day ; but if geckos be shut u]) with sand-flies they are freely 

 bitten at any hour and one lizard may have several flies biting it 

 at once. The author regards this as affording an explanation of 



