314 Annals Entomological Society of America [Vol. IX, 



varying from six to nine millimeters in length. The black 

 markings of the abdomen vary in extent, and from comparison 

 with eastern specimens {P . flavipes Gray), I can find no constant 

 difference and believe them to be the same." From compar- 

 isons made by the writer it is noted that the species, P. misella, 

 seems to be founded on color pattern alone, for there seems to 

 be no morphological dissimilarity. The only solution to such 

 questions of the identity of a species seems to be by a careful 

 study of a series of specimens which have been reared from 

 known forms. 



OVIPOSITION OF PTERODONTIA. 



On August 7, while passing by the border of an open hickory 

 grove, the writer observed several large flies hovering up and 

 down the trunks of some large hickory trees. The capture of one 

 of these proved the species to be identical with those reared from 

 the larvae found on the apple trees. The flies were observed 

 for some time ; during this period they hovered up and down the 

 tree trunks from about a foot above the ground to a height of ten 

 to fifteen feet. They flew always on the leeward side and from 

 one to two inches away from the surface of the bark. Occasion- 

 ally they would come to rest upon the bark, and at such times 

 they were so sluggish that it was possible to pick them up in 

 one's fingers. Though the flies were observed very closely, 

 they were not seen to deposit eggs or to pay any attention to 

 the gray jumping spiders that crept over the bark. 



Upon returning to the laboratory and transferring a living 

 specimen to a bell- jar, the writer noted that the handkerchief in 

 which it had been carried was sprinkled with minute black 

 specks, which on examination proved to be eggs. Further 

 observation revealed the fact that the eggs were forcibly dis- 

 charged from the ovipositor in extremely rapid succession and 

 that the eggs when first deposited were coated with a sticky 

 substance which caused them to adhere to whatever they hit 

 or fell upon. 



The following day some of the trees in the grove were banded 

 with narrow strips of clean, white paper. After a brief period 

 two flies appeared hovering over the surface of the bark in the 

 same manner as observed during the previous day. This time, 

 however, with the aid of the white paper strips, their actions 

 were easily interpreted. By watching closely as the flies hovered 



