4 HENRY F. CARTER. 



when water was relatively scarce. Weiss, on the other hand, states that at Tabeditt, 

 South Tunis, L. kerteszi and Simtdium maculatum, Mg. (S. lineatum, Fries) occur in 

 common swarms, and show such close association as adults that he believes the 

 immature stages of the two flies will be found near together. In this connection I 

 am indebted to Dr. J. M. Aldrich, of the United States National Museum, for the 

 following interesting observation, which indicates that the larvae of L. torrens, at 

 least, are terrestrial in habit. He writes : " Several years ago, before my connection 

 with the Museum, I identified a few specimens as Tersesthes torrens. The two females, 

 which I retained in my private collection, have labels reading, ' Maxwell, N.M. Reared 

 from pupae of Tachina mella, Webster. No. 11154. C.K.Wildermuth.' The 

 significance of the rearing record is that the adults made their appearance in a breeding 

 cage containing pupae of the fly ; this proves not parasitism, but that the larvae are 

 terrestrial, as is known to be the case in some of the Ceratopogoninae." 



A perusal of the data subsequently given in the systematic portion of this paper 

 in connection with the habitats of the different species provides some indication of 

 the types of country in which these flies are known to occur, and of the avidity with 

 which they bite. It will be seen that they have been found in what appear to be 

 both relatively dry and well-watered districts, also in low-lying as well as mountainous 

 regions. Noe states that L. irritans is especially prevalent in the coastal plains of 

 the Roman Campagna. Langeron records L. kerteszi from marshy places in the desert 

 in southern Tunis ; Willcocks (1918) has observed the same insect in the Nile delta ; 

 while Weiss, Townsend (1893) and others have found species at altitudes varying 

 from 1,600 ft. to 7,000 ft. vSo far as is known, they are diurnal insects, continuing 

 their activities throughout the hottest parts of the day. Noe states that in Italy 

 L. hezzii and L. irritans (locally known as ' serapiche ') appear towards the end of 

 May, reach their maximum abundance about the middle of June, and then gradually 

 decrease in numbers and disappear early in September. The females of several species 

 are known to bite man and his domestic animals, and to the former at least sometimes 

 cause great annoyance and inconvenience. In some districts they have gained an evil 

 reputation, and indeed at certain seasons would appear to be very serious pests, since 

 at the period of maximum abundance the females of some species attack in dense 

 swarms. According to Noe, L. irritans may occur in such swarms that no defence 

 is possible, and he adds that labourers working on the railway from Rome to Pisa 

 were sometimes forced to take shelter in order to escape these massed attacks. L. 

 kerteszi is also known to adopt this habit (Weiss), and Sambon (1913) states that 

 Chalmers in the Nile delta " obtained from the fellahin a very definite history of small 

 black, blood-sucking flies appearing in swarms, and Dr. Gough told him that this fly 

 scourge of the delta is undouVjtedly Leptoconops ; " Chalmers was unable to find 

 Simnlium in this region, but L. kerteszi is abundant in certain localities (Willcocks). 

 Pratt (1907), writing on North American blood-sucking midges, says that Barber 

 considers Leptoconops [Tersesthes] " much worse as a pest than any Ceratopogon [sens, 

 lat.) he has ever encountered." The bites are painful and the subsequent local 

 reactions irritating and persistent ; L. irritans, in addition, also causes considerable 

 discomfort by crawling about the body, among the hair, beneath the clothes, in the 

 ears, etc. (Noe). Noe's observations, however, tend to indicate that in some 

 respects the habits of different species are not identical ; L. bezzii is said to prefer the 

 neighbourhood of houses and outbuildings rather than the open plains, and to be 

 particularly attracted by poultry, in the houses of which the females shelter over- 

 night. Further, although the females apparently prefer blood for food, Noe has seen 

 both sexes of this species on flowers, and remarks that the males are especially fond 

 of Euonymus. 



Association with Disease. 



Grassi (1901) endeavoured to obtain the experimental infection of L. irritans, Noe, 

 with malaria parasites. He fed twenty-eight "wild" females of this species upon 



