V] LIFE-CYCLE 39 



reason. In Malta, Newstead found that bedrooms on the first 

 floor facing the sheltered side of the house were much more 

 favoured than those of the opposite side ; and only a single 

 example was ever found in rooms on the second floor. Some 

 persons seem to be immune to the attacks of these insects, 

 as for some reason they have their likes and dislikes with regard 

 to hosts, as well as habitat. It is probable that reptiles 

 constitute the main hosts of these insects, for in West Africa, 

 Roubaud found a lizard covered with gorged females of 

 P. minutus. More recently Howlett has brought forward 

 convincing evidence to shew that in India geckos are the 

 chief hosts and are preferred to man. 



The flies are especially abundant in the hot season of the 

 year but in tropical countries they may be found at all times. 

 When kept in captivity on wet blotting-paper P. papatasii 

 lives but a short time (3-9 days), even though fed on human 

 blood and kept under the most favourable conditions. The 

 life of the adult therefore is probably of but short duration. 

 The females readily oviposit in captivity but often die during 

 the process. From an examination of the ovaries, the number 

 Df eggs is found to be from 40 to 50, so that the insect is 

 comparatively little prolific. 



Life-cycle, After copulation, the female seems to require a 

 feed of blood before being able to lay any eggs. This condition 

 having been fulfilled, the insect then retires to some dark corner 

 and deposits her eggs either singly or in clusters, the total 

 number varying from 30 to 80, according to the species. The 

 act of oviposition is accompanied by very extraordinary move- 

 ments on the part of the female. The whole process has been 

 described by Newstead in the case of P. papatasii. A gravid 

 female was placed into a glass-topped box and supplied with 

 wet blotting-paper, when the insect at once settled on the paper 

 and brought her proboscis into contact with it. After a few 

 seconds she appeared to become intoxicated and collapsed, 

 crossing the middle- and hind-legs behind the abdomen, whilst 

 the front pair remained in their normal position. The abdomen 

 was then raised and fully extended, after which three eggs 

 were laid at short intervals. Each egg was ejected with 



