206 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 
persistently remain in the uppermost recesses of the cage and refuse to 
come down. 
All in all, the disadvantages were so many, in proportion to the 
advantages, and these latter were so largely imaginary in point of fact, 
as to result in the decision to discontinue the use of the large cages 
entirely in 1908. 
The cage figured by Mr. Townsend (PI. XV) was, however, an 
innovation in several respects. It was built independently of any 
tree winch should serve as food for the inclosed caterpillars, but 
these caterpillars were confined within certain restricted limits and 
exposed to the attack of the tachinid flies at one and the same time 
by the use of the open "tanglefooted " tray. Here a most distinct 
advantage was gained. The floor of trodden earth (subsequently 
replaced by cement) effectually prevented the entrance of numerous 
insects which were formerly uninvited guests and thereby removed 
another serious disadvantage. An arrangement of double doors 
and wire-screened vestibule prevented the untimely liberation of 
the flies, and there were no longer so many inexplicable disappear- 
ances. The fact that the top of the cage was flat instead of being 
extended into the gable tended to keep the flies somewhere more 
nearly where they were wanted. In short, there were a great many 
advantages possessed by the new cage which were not possessed by 
the old, and there was some justification for considering it good. 
In the meantime Mr. Burgess, who had taken over the Calosoma 
work in the fall of 1907, had developed the out-of-door cage along 
totally different lines, making it into nothing more than an out-of- 
door insectary (PI. XVI), in which were conducted practically all of 
his numerous and varied investigations. It had seemed in 1907 as 
though the only one among the numerous imported insects which 
had done at all well in the out-of-door cages as then used had been 
the Calosoma, but the success attending their use for the rearing of 
this insect was so soon and so overwhelmingly eclipsed by the success 
which attended the use of small individual cages for single pairs of 
the beetles or individual larvae as to render the advisability of their 
discontinuation for this purpose emphatic. 
Some attempt was made to use the tachinid cage in 1909, but not 
to the extent to which it had been used the previous year. Late 
in the summer of 1909 reproduction experiments with small numbers 
of various species of tachinids were undertaken by Mr. W. 11. Thomp- 
son, who used cages constructed after the familiar Riley type, but 
covered entirely with coarse fly screen. (PI. XVII, fig. 1.) He 
succeeded in much of that which he undertook to do, and in 1910 
continued the use of this type of cage, for a part of a quite extensive 
series of most interesting and successful experiments, but he also 
used a much smaller cage consisting of a wire-screen cylinder (PI, 
