118 MISCELLANEOUS PAPERS. 



This is certainly an excellent showing for adaptation and variety of 

 habit in a family as compact in character as the Tachinidse, which 

 does not include the macronychiids, muscids, or phasiids, and in 

 which a certain unity of habit was long supposed to obtain. It may 

 be further remarked that we have in one instance dissected two female 

 specimens, separated with difficulty on slight external characters, 

 and appearing at first to be the same species, and have found one 

 to have the habit of leaf-oviposition and the other, a habit of either 

 host-oviposition or host-larviposition. This aptly illustrates the 

 necessity for a most careful study of external adult characters and a 

 nice sense of discrimination — in other words, the zoological sense — 

 in order to distinguish the many distinct but often closely similar 

 forms of these Hies. Slight differences in shade of pollinose cover- 

 ing, in width of front, in strength of frontal bristles, in hairiness of 

 eyes, and in thoracic and abdominal lines — all of these easily over- 

 looked — were the only external characters that enabled us to pro- 

 nounce the two specimens distinct species. The character of the 

 uterine eggs, however, at once demonstrated the very marked dis- 

 tinctness of the two forms, which can not be referred to the same 

 genus, nor even to the same tribe, and perhaps not even to the same 

 subfamily. 



The five classes of reproductive habit mentioned above are arranged 

 in the order of their probable antiquity, host-oviposition being con- 

 sidered the oldest and leaf-larviposition the most recent. This order 

 not only seems natural from the reproductive standpoint, but is borne 

 out by a study of the external characters of the flies themselves, prin- 

 cipally the character of the facial plate. 



CONCLUSION. 



The results of all this work on European, Japanese, and American 

 tachinids point to the very great importance of Blepharipa scuteVata 

 and Crossocosmia sp. as parasites of Porthetria dispar. The great 

 capacity for reproduction, possessed by these species, and the fact 

 that all of their eggs must be eaten by the caterpillars wherever 

 dispar is abundant, place them in the lead of parasites. 



No two species can be so relied upon as parasites of Euproctis 

 chrysorrhma^ but the Japanese Tachinas, Trieholyga grandis^ Comp- 

 silura eondnnata, Dexodes nigripes, and Parexorista chelonice seem 

 to be among the most important here. 



All of the other imported species mentioned will prove of much 

 importance as aids in the control of one or both of these moths. The 

 great majority of them are parasitic on both hosts. 



O 



