EGG PARASITES OF THE BROWN-TAIL MOTH. 259 
A large number of parasitized eggs, containing the brood in various 
stages of development, were placed in cold storage and kept until 
the following June and July, when, upon being removed, a few of 
the parasites completed their transformations. With these as pa- 
rents large numbers were reared in the laboratory upon the fresh 
eggs of the brown-tail moth, at that time abundantly available, and 
the cold-storage experiment was repeated during the winter of 1908-9 
with much better results than before. An abundant supply of parent 
females was available in the summer of 1909, and a great many 
thousands of the parasite were reared and liberated under the most 
favorable conditions which could possibly be desired or devised. 
Many thousands were known to have issued from parasitized eggs 
contained in small receptacles attached to the branches of the trees 
upon which the brown-tail moths were even then depositing eggs 
in abundance. 
No false hopes were felt as to the probable success of this venture. 
It has been amply demonstrated in the laboratory that the females 
were unable to penetrate the egg mass for the purpose of oviposition, 
and the location in the mass of the few eggs parasitized by the 
American race of pretiosa indicated sufficiently well the inability of 
that species to do better in the open than either it or the European 
would do in confinement. 
Accordingly no disappointment was felt, when it was found that 
the degree of parasitism effected by the European species in the 
immediate vicinity of the colony sites was hardly, if any, greater than 
that ordinarily effected by the native species. It is hardly a physical 
possibility for Trichogramma to effect more than a small percentage 
of parasitism in the egg mass of the brown-tail moth, and the value 
of the genus as represented by the three species or forms which have 
been studied at the laboratory is slight. 
At the same time, it is not felt that the labor which has been 
expended in an attempt to give Trichogramma a fair test has been 
altogether lost. There are numerous other hosts upon which it is 
a very efficient parasite, and it is easily conceivable that at some 
future time it will be found possible to utilize it in some manner 
which the circumstances themselves will suggest. 
As a possible example may be mentioned the tortricid Archips 
rosaceana Harris, which at times becomes a pest in greenhouses 
devoted to the growing of roses. In Volume II, No. 6, of the Journal 
of Economic Entomology, Prof. E. D. Sanderson describes such an 
outbreak in a large rose house in New Hampshire under the heading 
of ‘‘Parasites.”’ Prof. Sanderson says: 
The outbreak observed by us furnished a case of the most complete parasitism we 
have ever seen. When first observed, in late July, from one-third to one-half of the 
eggs were parasitized by a species of Trichogramma. Two weeks later it was difficult 
