contains an egg or larva of a parasite^ nor lias one. of tliem been 

 known to consign a greater nunibei of eggs to an insect than the 

 nnniber of larv.T, wliicli that insect can maintain. On the contrary, a 

 Tachina fly has rei)eatedly been known to attach to a caterpillar three 

 or four times as many eggs as the number of larva^ the caterpillar can 

 maintain. Owing to this fact, a great many tachinid larviii must neces- 

 sarily perish for want of food, while several which have barely had a 

 sufficient quantity to keep them alive will be considerably dwarfed in 

 size, as compared to their more fortunate brothers, and thus it will 

 sometimes happen that some of the adult flies will be only one-half, 

 and in rare instances even only one-third, as long as others which were 

 the progeny of the same parent. Certain systematic writers, who have 

 had no experience in rearing these flies, lay great stress on a difference 

 in size as indicative of a distinct species; but our breeding records 

 have abundantly demonstrated the fact that one specimen may be 

 fully three times as long as an other and yet both belong to one and 

 the same species. 



TACHINID FLIES AND THEIE, HOSTS. 



The following is a list of the Tachina flies that have been bred by 

 this Division, together with the hosts from which they were bred. By 

 iar the greater number of these were reared in the department insec- 

 tary, in charge of Mr. Theo. Pergande. A few additional species, speci- 

 mens of which have been studied by the writer, are included in this 

 list. Of the published records, only those are included where the flies 

 have been bred from other hosts than those from which this Division 

 and its correspondents have reared them ; such species are indicated 

 by asterisks (* ) in addition to the names of the persons who reared them 

 and to the i^ublished references. A few of the breeding records, which 

 are evidently erroneous, are preceded by a mark of interrogation ("?). 



The list is in two parts, arranged alphabetically: 



I. — Parasites and their hosts. 

 rarasites. Host insects. 



Acemyiai (lentnta Coq Chor(o])liaf>a viridifasoiata DeG. Bred by T. Per- 



j^ando Jinio 26, 1877, from an adult collected .Jiiuo 

 11 at St. Louis, Mo. 



Admontia deiuylus Walk Lophj'rns abbotii Leach. Issued June 24, 1882, 



from a larva collected by E. A. Schwarz;, in Mary- 

 laud. 

 Lophyrus lecontei Fitch. Issued May 6, 1886, from 

 a larva collected by T. Pergande in Virginia, 

 October 10, 1885. 



Admontia retinia' Coq Retinia. sp. Bred April 17, 1888, by A. Koebele, 



Alameda, Cal., from a caterpillar found in a bud 

 on VinuH insirjnis. 



Auiobia. distiiicta Town Acronycta dactylina (Irotc. Issued Marcli 24, 1884, 



from a caterpillar collectcsd by A. Koebelo at 

 Holderness, N. H., September 2G^ 1883. 



