282 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, 1 or what was equally suitable, a strip of 

 ordinary mosquito netting, would be spread over the pile of debris 

 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 pallipeSj 

 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; in 

 any event, only about 250 of the cocoons were secured, when it was 



i This paper was originally imported from Franca for use in a similar manner in rearing silkworms. 



