A STUDY OF COMPSILURA CONCINNATA. 15 
but owing to the high percentage of mortality, due to the so-called 
wilt disease, few survived long enough to be used in the experiments. 
In the spring of 1916 efforts were made to secure more of the para- 
site-free material, with the result that the writer was more success- 
ful than before. A large number of brown-tail moth larve were 
reared from the webs, and several thousand gipsy-moth larvee were 
hatched out. These hosts were kept in large “tanglefooted” trays, 
which were covered with fine screen cloth, to prevent any possibility 
of parasitism being effected from outside sources. Through the 
cooperation of the assistants of the Bureau of Entomology at the 
Bussey Institution an abundance of parasite-free material was se- 
cured of the species Bombyx mori L., Hemerocampa leucostigma 
S. & A., and Callosamia promethea Drury, which had been reared 
in a greenhouse, where it was impossible for parasitism by Comp- 
silura to take place. 
LARVA AND PUPA STAGES. 
The conditions under which the life history of Compsilura was 
studied were so different from the normal that no doubt it varies 
from that actually obtaining in the field. Nevertheless, as nearly 
the normal environment of the fly as was possible under laboratory 
conditions was simulated. 
The length of the larva stage in Compsilura varies with the 
season, being unaffected by temperature to any appreciable extent. 
Tables III and VI indicate the length of the larva stage under 
laboratory conditions. As shown, the adult flies were of varying 
ages at the beginning of each experiment, this apparently affecting 
the length of the larva stage. The length of the stage for each larva 
was computed from the time the experiment was begun, for it was 
impossible to note the time at which each adult attacked the host 
larva. The length of the pupa stage is also shown in Tables III and 
VI. The puparia used in these experiments were removed from the 
various trays as soon as they had hardened and become the charac- 
teristic dark-brown color. 
Tapiy IlI.—Length of larva and pupa stages of Compsilura concinnata under 
laboratory conditions, Melrose Highlands, Mass., 1916. 
Age of Proportion 
iamiale Murmt A hey of sexes. 
art Comp- pried jae: se Number| Average 
Tent silura pri in ern of pupa-| length Number and |Species and stage 
vat when prema il Messe: ria that | of pupa stage of hosts, of host. 
, begun. experi- larve | stage of emerged.| stage Fe- ’ 
4 *perl- | secured. | Compsi- Bed.) Slabe- | Male.| _- © 
ment lura, male. 
began. f 
1916. Days. Days. 
July 13 3 28 16.64 24 12 13 11 | 100, fourth stage} Brown-tail moth, 
larvee. 
17 17 6 9. 83 3 14, 50 2 1 | 50, fourth stage. Do. 
6 6 19 13.57 15 10. 40 7 8 | 60, third and |Gipsy-moth, 
fourth stages. larvin. 
