SYRPHIDAE OF MAINE. 155 



was placed out-of-doors on the original Cornus leaves, inside a 

 cheese-cloth bag. Here it remained without striking change, 

 gradually becoming dryer and more attenuated, until Sept. 12 

 when it was recovered but later died. 



On July 24, 1916, Mr. G. B. Newman collected a nearly full 

 grown, and three very small, larvae of this species among Chait- 

 ophorus popitlicola Thomas on poplar. The smaller ones were 

 decidedly greenish in color, the large one tan. This green color 

 gave place in the laboratory to an ashy- or faint-green which 

 persisted for a week or more. On August 2, two of them were 

 decidedly tan colored and by August 5 all had become so. 



There was as yet no clue whatever to the identity of the 

 larvae under consideration, and it proved a most difficult species 

 to rear. Those kept in pint jars in-doors, even when most atten- 

 tively supplied with their chosen food, fresh daily, fed and grew 

 rapidly to full size, and then gradually became senescent, more 

 and more sluggish, and after a time refused to feed or to move 

 or to pupate, becoming more and more attenuated, thinner and 

 dryer, and moving about only when disturbed until months la- 

 ter when they appeared finally to be lifeless. Sterile soil and 

 decayed wood were provided in the bottom of the cages for pu- 

 pation but without success. Much the same experience resulted 

 from attempts to rear them in field cages or cheese-cloth en- 

 closures on the living infested plants out-of-doors. 



On August 8, 1916 a number of eggs were found in company 

 with a dozen or so of larvae of various sizes scattered along the 

 smaller twigs of willow trees infested with Pterocomma smithiae 

 (Monell). These eggs began hatching on August 13 and at once 

 disclosed the fact that they were conspecific with the flattened 

 brownish larvae. The eggs, while of about the average size for 

 this group, presented a microscopic spider-web sort of pattern 

 on the chorion which was so characteristic that, in view of the 

 difficulty of rearing adults from the larvae, the attempt was at 

 once made to capture gravid females which should disclose the 

 same kind of egg and so accomplish the determination of the 

 species. 



Finally on August 25, Mr. Newman captured about one of 

 the infested trees a female of X ant ho gramma diuisa. She was 

 confined indoors about 10 A. M. and by 2 P. M. had deposited 

 a single egg, another by 2.45 P. M. and four more during the 



