THE BLACK FLY. 



73 



The Simulium molestura (Fig. 68, enlarged), as the black fly 

 is called, lives during the larva state in the water. The larva 

 of a Labrador species (Fig. 69, enlarged) which we found, is 

 about a quarter of an inch long, and of the appearance here indi- 

 cated. The pupa is also aquatic, having long respiratory fila- 

 ments attached to each side of the 

 front of the thorax. According to 

 Westvvood, "the posterior part of its 

 body is enclosed in a semioval mem- 

 branous cocoon, which is at first formed^ 

 by the larva, the anterior part of which 

 is eaten away before 

 changing to a pupa, so as 

 to be open in front. The 68 - Black F1 y- 



imago is produced beneath the surface of the water, 

 its fine silky covering serving to repel the action 

 of the water." 



Multitudes of a long, slender, white worm may 

 often be found living in the dirt, and sour sap run- 

 ning from wounds in the elm 

 tree. Two summers ago we 

 discovered some of these lar- 

 va3, and on rearing them found 

 that they were a species of 

 Mycetobia (Fig. 70 ; a, larva ; 

 6, pupa). The larva is remark- 

 able for having the abdominal 

 segments divided into two 

 portions, the hinder much 





69. Black Fly 

 Larva. 



smaller than the anterior divi- 

 sion. Its whole length is a 



little over a third o, an inch. The pupae 



were found sticking out in considerable 



numbers from the tree, being anchored by 



the little spines at the tail. The head is 



square, ending in two horns, and the body is straight and 



covered with spines, especially towards the end of the tail. 



They were a fifth of an inch in length. The last of June the 



flies appeared, somewhat resembling gnats, and about a line 



long. The worms continued to infest the tree for six weeks, the 



flies remaining either upon or near it. 

 7 



