982 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 
the rearing of the Apanteles was simplicity itself, compared with the 
similar process the year before. A large sheet of paper, thickly per- 
forated with small holes,t or what was equally suitable, a strip of 
ordinary mosquito netting, would be spread over the pile of débris 
in each tray and fresh food placed on it. In the course of 24 hours 
the great majority of the caterpillars would have crawled upon this 
paper or netting, and could be removed instantly, and with scarcely 
any disturbance, to a fresh tray. The sorting over of the contents 
of the tray in which they had been feeding, for the cocoons of their 
parasites, could then be conducted without the annoyance of their 
presence, and with a minimum of discomfort. This is, of course, the 
same method used in feeding the silkworm of commerce. 
In all some 15,000 cocoons were secured in this manner, but only 
about 10,000 of the adults were reared and liberated. Some 100 of 
the cocoons produced the secondary parasite Mesochorus pallipes, 
and a considerably larger number a small pteromalid, which was 
vaguely familiar in appearance, but which was not at that time recog- 
nized as identical with Pteromalus egregius, concerning which so much 
has already been written. 
The Apanteles were carefully separated from their enemies and 
three colonies were established in the field. Two of these were 
rather small, but one of them was made very large, and to comprise 
more than two-thirds of the total number reared. It was no longer 
a question that the small colony was sometimes a mistake, and that 
it was invariably safer to liberate large colonies and to establish the 
species first of all, and to bring about dispersion later, if artificial 
dispersion should appear to be necessary. 
It is interesting to note, in this connection, that neither in 1909 
nor 1910 was it possible to find any trace of the Apanteles in the 
neighborhood of either of the two smaller colonies mentioned above, 
while from the larger it was recovered in 1909, and by 1910 had spread 
to a distance of several miles at least. 
The third lot of nests, which was placed in cold storage before the 
caterpillars became active in the spring, was left there until early in 
July, when it was removed. A part of the caterpillars immediately 
became active, but it was at once evident that many of them had 
died as a result of the unnatural conditions. The weather was 
exceedingly hot immediately following and suitable food for the young 
caterpillars could not be obtained. In consequence, a great many of 
them died from one cause or another, or from a combination of sev- 
eral; the larger part of the caterpillars died soon after having become 
active, and it seemed as though those containing the Apanteles 
suffered much greater proportionate mortality than the others; m 
any event, only about 250 of the cocoons were secured, when it was 
1 This paper was originally imported from France for use in a similar manner in rearing silkworms. 
