470 OTHER BLOOD-SUCKING FLIES 



do not pupate until the following spring. When, after several 

 moults, they go into the resting pupal stage the last larval skin 

 with its caudal bristles remains adhering to the posterior end. 

 The pupa (Fig. 212C) is characterized by a very rough cuticle 

 over the thorax, but can be identified best by the adhering larval 

 skin. It is colored so much like its surroundings, and looks so 

 much like a tiny bit of amorphous matter, that it is very difficult 

 to find. In warm weather the adult insect emerges after from 

 six to ten days, but this is much prolonged by low temperatures. 

 The entire life cycle from the laying of the eggs to the emergence 

 of the adults may be passed through in a month in hot weather, 

 according to Hewlett's observations on an Indian species, though 

 it takes two months or more in cool weather. In Malta, accord- 

 ing to Newstead, the cycle takes about three months. 



Phlebotomus and Disease. Phlebotomus Fever. Although 

 sandflies have been accused of transmitting a number of human 

 diseases in various parts of the world, in most cases their actual 

 role has not been determined beyond doubt. The most im- 

 portant relation of sandflies to disease is in connection with a 

 relatively mild febrile disease sometimes known as three-days, 

 fever, but more commonly known as phlebotomus fever or 

 papataci fever from the name of the transmitter, Phlebotomus 

 papatasii. The nature of the disease and the r61e of the sandfly 

 in carrying it is discussed in Chap. X, p. 188. As in the case 

 of many other insect-borne diseases, the relation of the insects 

 to the disease was suspected for a long time before the scientific 

 proof of it was made. It was not until 1908 that Doerr demon- 

 strated the part played by sandflies. 



The principal species concerned in the transmission of phle- 

 botomus fever is P. papatasii, but it is possible that other species, 

 especially P. perniciosus and P. minutus, both of Mediterranean 

 countries, may also be involved, though as far as is known the 

 disease does not occur outside the range of the first-named species 

 except at Aden. 



P. papatasii (Fig. 212D) is of medium size, reaching about one- 

 eighth of an inch in length, pale yellowish gray in color with 

 a dull red-brown stripe down the middle of the thorax and a spot 

 of the same color at either side. It is found in many parts of 

 southern Europe, North Africa and in southern Asia. It has 

 the typical habits of the genus, preferring to lay its eggs in 



