4 MAINE AGRICULTURAL EXPERIMENT STATION. I9II. 



elongate oval in outline, flattened on one side. About 2 days 

 after deposition the larv?e emerge through a longitudinal slit. 

 The nearly transparent larvse, within a few hours begin the con- 

 struction of their cases or tubes. As the insects were confined 

 in glasses with tight fitting covers, and no males have been bred 

 this year, we have demonstrated here a case of parthenogenetic 

 reproduction. 



Sifnulium and pellagra. 



The two species S. hirtipes and venustum, so common in 

 various parts of the northeastern states, were abundant during 

 the spring and summer in this vicinity. To those who have 

 camped in the woods or mountains where Simulium is abundant, 

 the bite of this short-bodied, hump-backed little fly is only too 

 well known. The females only are blood-thirsty. They are a 

 veritable scourge to the hunters and fishermen in Maine. Re- 

 cently some German veterinarians have shown that they are 

 the cause of a serious disease in cattle. More recently still 

 Dr. L. W. Sambon of England makes the claim that 5". reptans 

 is the transmitter of the disease Pellagra prevalent in the south 

 of Europe, which in the last 2 or 3 years has excited physicians 

 in the southern states. Sambon states that the disease follows 

 water courses and only persons much in the open are attacked. 

 These facts are peculiarly significant and here is the clue by 

 which a link may be added to the chain of circumstantial evi- 

 dence to establish the guilt or innocence of the gnat. The insect 

 breeds only in water which is shallow but at the same time swift. 

 If the larva be transferred to still water it will die in a very 

 few hours, but it may live for several days in a situation kept 

 moist by trickling water. The larvae are found on rocks and 

 debris, particularly in little brooks, and the adult flies are never 

 found at a great distance from such localities, rarely entering 

 houses. If Sambon is correct in. his view we must assume that 

 a person afflicted with pellagra has been in the open in the vicin- 

 ity of a brook or stream where Simulium abounds, at a com- 

 paratively recent period prior to his infection. 



Simulium reptans, the species which is accused of carrying 

 the infection in Europe, has been thus far only recorded from 

 Greenland on the western hemisphere. This, however, in itself 

 would be no bar to the acceptance of the theory, since we know 

 that in the case of malaria several species of Anopheles are con- 

 cerned in the transmission of the disease. 



