99 wanting, there being only birds to supply this, makes the problem a puzzling one. In spite of this, the species of these flies are numerous, the individuals sometimes abundant, so much so as to furnish the food supply for the larvae of various Hawaiian Crabronidae. Five species of Pipunculus (parasitic here on Delphacid leaf hoppers) are known to m.e from Kilauea, and several of Caenosia, and these with the groups previously mentioned, as well as species of Lispe, Asteia, Tephritis and Sarcophaga complete the Dipterous fauna. Throughout this paper I have used generic and specific names, as published in the " Fauna Hawaiiensis, " so that it has not been necessary to cite the authors. In the Hymenoptera I have used the genera proposed by me subsequently for the genus Crabro of that work. Papers. On Some Peregrine Aphidae in Oahu [Hem.] By G. W. KiRKALDY. With the exception of certain Chermidae, all the Sternorr-hynchous Homoptera yet observed in the Hawaiian Archi-pelago appear to be recent arrivals. As is natural in families so little studied till lately, many of the species cannot be identified with any of those already described from other Faunas and consequently their endemic habitat remains unknown. I now enumerate four Aphidae occurring near Honolulu; about six more are known to me, but as they belong to obscure genera with many, poorly differentiated species, I have not yet positively determined them, and must leave them for a future communica-tion. Several of these species are of considerable economic import-ance, Myzus citricidus doing much damage to Orange trees, whilst Aphis sacchari is a pest of Sugar-cane. Aphis Linnaeus. 1758 Systema Naturae, Ed. 10, p. 451. 1. sacchari Zehntner. Aphis sacchari Zehntner 1897 Arch. Java Suiker. V. p.? and 1901 op. c, IX (sep., p. 1) PI. I f. 1-10; Kriiger 1S99 Das Zuck-errohr und seine Kultur 313.