TACHIXID PARASITES OF THE GIPSY MOTH. 
207 
XVII. fig. 2, at right), about 8 inches in diameter and 12 inches high, 
with wooden top and bottom. His best results were secured through 
the use of this cylinder, and the reason appeared to be that the flies 
were less likely to fly and acquire sufficient momentum to injure 
themselves in small than in Large cages. 
In elaboration of the principle apparently involved, a still smaller 
cylinder (PI. XVII, fig. 2, at left), scarcely 3 inches in diameter and 
shorter than that formerly used, was experimented with. Better 
results than ever before were secured upon the single occasion upon 
which this cage was used, and unless further experimentation results 
in additional modifications or in a reversal of the results first obtained, 
the cvlinder cage figured herewith will be used almost exclusively 
in 1IM1. 
As a basis for comparison of the utility of the Large versus the 
small cage-, the results attending (he investigations into the biology 
of Blepharipa may be taken as an example. 
Between 300 and 400 Hies were used in an attempt to secure 
oviposit ion ill the large cage iii 1908, and no care that could be given 
them under these conditions was lacking. Not a single female com- 
pleted her sexual development to the point at which she was capable 
of depositing fertile eggs, and no eggs of any sort were secured. 
Scores instead of hundreds of flies were used for the experiments 
in the spring of 1910, and many of the females lived throughout 
the period allotted for the incubation of their eggs and deposited 
them at the rate of several hundred daily, and abundant opportunity 
was thus aH'onled for the continuation of the studies into the lives 
and habits of the young larva? under dill'erent conditions and in 
different hosts. 
In short after the most thorough tests, the use of the large out-of- 
door cages has been definitely abandoned for all phases of the work 
at the gipsy-moth parasite laboratory. It is not. however, intended 
to state thus dogmatically that similar large cages would not be 
adaptable to work with parasites of any other host. 
ffYPERPAKASITES ATTACKING THE TAGHHTHXB. 
Undoubtedly there is abroad an important group of secondary 
parasites of the gipsy moth and the brown-tail moth, included in 
which are some which attack the various species of tachinids to such 
an extent as indirectly to affect the welfare of the primary host. 
Very little is known of this hyperparasitic fauna, because practically 
all of the tachinids received have been from host caterpillars which 
were living at the time of collection. That it exists is well indicated 
by the tentative studies of the American parasites of Compsilura 
concinnata, which were made in 1910, and which will be the subject 
of mention at another place. 
