y) 
contains an egg or larva of a parasite, nor has one of them been 
known to consign a greater number of eggs to an insect than the 
number of larve which that insect can maintain. On the contrary, a 
Tachina fly has repeatedly been known to attach to a caterpillar three 
or four times as many eggs as the number of larvie the caterpillar can 
maintain. Owing to this fact, a great many tachinid larvee 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 THEIR 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 
far 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 published references. A few of the breeding records, which 
are evidently erroneous, are preceded by a mark of interrogation (7). 
The list is in two parts, arranged alphabetically: 
I.—PARASITES AND THEIR HOSTS. 
Parasites. Host insects. 
Acemyia dentata Coq .---------- Chortophaga viridifasciata DeG. Bred by T. Per- 
gande June 26, 1877, from an adult collected June 
11 at St. Louis, Mo. 
Admontia demylus Walk....---- Lophyrus abkbotii Leach. Issued June 24, 1882, 
from a larva collected by E. A. Schwarz, in Mary- 
land. 
Lophyrus lecontei Fitch. Issued May 6, 1886, from 
a larva collected by T. Pergande in Virginia, 
October 19, 1885, 
Admontia retinize Coq ..-..----- Retinia sp. Bred April 17, 1888, by A. Koebele, 
Alameda, Cal., from a caterpillar found in a bud 
on Pinus insignis. 
Amobia distincta Town .....---- Acronycta dactylina Grote. Issued March 24, 1884, 
from a caterpillar collected by A. Koebele at 
Holderness, N. H., September 26, 1883. 
