100 



The fall-growQ larv?e of the Simulium are the largest I have ever seen. 

 Speciraeus were takeu which were afterwards measured aud found to 

 be between three-fourths and seven-eighths of an inch long. Tlie anal 

 swelling is very i3ronounced. Those colonies which were left by the re- 

 ceding watei" seemed to make no effort to escape but probably died on 

 the spot to which they were attached. A gradation in the size of the 

 larvae from the borders of the stream to the center was observed, as al- 

 ready noticed by Dr. Barnard. The cocoons were found here and 

 there, but apparently usually a little distance awaj' froui the masses of 

 larvie. The cocoons appeared to me exceptionally large and tough. 

 The colonies of larvae were found in greatest numbers just on the 

 verge of the numerous falls where the water was shallow and swift, and 

 at the crown of these falls I was delighted to have Professor Comstock 

 point out to me the adult insects. They were hoveriug in the bright 

 sunlight in considerable numbers, and a number were captured with a 

 net. They could hardly be said to fly in swarms, but seemed to hover 

 about, each one independent of the others, but remaining in about the 

 same locality. At this time of the year they seemed to be principally 

 males, as of the fifty specimens captured but one was a female. 



Professor Comstock tells me that this same flight of the adults can 

 be observed on almost any day through the summer, and that he has 

 seen them as early as June. During July he states that he observed 

 them flying in enormous numbers. His notes upon the oviposition of 

 the species will be very interesting when published. It will be re- 

 membered that Dr. Barnard observed the eggs at Buttermilk ravine at 

 the edge of the steam cibove the water. Professor Comstock, however, 

 has seen the female dart at the crown of the falls after a preliminary 

 hover and lay her eggs in the swift current. - He states that a number 

 of females choose the same place for oviposition and frequently lay a 

 mass of eggs as large as the i)alm of one's hand, which accounts for the 

 large extent of the colonies of larvae. I have seen these larvae in 

 patches of many feet in length and so close to each other that the surface 

 of the rock could not be seen. The jet black color of the larvie is strik- 

 ing, and the colonies can be readily seen from a considerable distance. 



A X5eculiar fact concerning this species is that it does not seem to bite. 

 No one, so far as I know, has ever been bitten by a Black Fly in this 

 viciUity. A comparative examination of the mouth-parts of this and 

 other species will therefore be interesting. The nniles are very beauti- 

 ful, as are individuals of this sex in other species of the genus. The 

 eyes in life are of a beautiful golden bronze, the body is covered with a 

 silvery pubescence and the wings are highly iridescent. 



The exact details of the life history of this species are being collected 

 by Professor Comstock, and we look forward to their publication with 

 much interest. 



I called attention three years ago to the abundance of the nets and 

 tubes of Hydropsychc ui)on the Simuliumcovered rocks in Rock Creek 



