SIMULIUM. 67 



not appear to be guilty of biting man. It has, on the other hand, 

 been clearly proven that forhesi is given to attacking man and also 

 stock. As it occurs in great numbers there is a possibility of its 

 doing considerable damage, although as a general rule it is not very 

 troublesome away from the river. Mr. C. A. Hart has found speci- 

 mens of SimuUum forhesi in Mason County, over 5 miles southeast of 

 Havana. As the nearest possible breeding place of the species is the 

 Illinois River, it is evident that the species can fly for a considerable 

 distance. As there was no appreciable diminution in the numbers 

 of the species at this distance it was quite clear that these were not 

 merely accidental stragglers, whose presence was due to their being 

 carried by stock or otherwise, and that the ditches, which are very 

 small in that vicinity and never present favorable breeding quarters 

 at any time, could not possibly have stocked the country so thoroughly 

 with the insects. No extended investigations were carried out to dis- 

 cover the extent of the area covered by the species, but according to 

 reports obtained, and which there is no reason to discredit, the range 

 of the species was considerably wider than ascertained by Mr. Hart. 

 No evidence has been discovered to prove that johanTiseni or forhesi 

 live in the larval stage in ditches such as are present in the part of 

 Mason County above referred to. 



It may be of interest to mention that the agents of the Illinois State 

 Laboratory of Natural History have found the parasites mentioned 

 by Strickland commonly in Simulium larvae in both the Illinois River 

 and the Sangamon River at near the source of the latter. So far as 

 the records indicate, vittatum was the only species affected, but the 

 percentage of parasitized individuals was very large. 



In the records of the work done by agents of the Bureau of Ento- 

 mology many years ago there occurs a note on these parasites, but the 

 fact was not mentioned in any of the published reports on the family. 



