196 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



cable to send any of the cocoons of the parasite until June and July; while in America 

 the season was early, and by that time all of the caterpillars, as has already been stated, 

 had pupated. In 1909 the season was rather early in Japan and correspondingly late 

 in America; and, besides, through special effort, Prof. Kuwana was enabled to send a 

 few thousands of the cocoons of the first generation, which reached the laboratory 

 early in June. About 1,000 adults emerged from these cocoons after receipt, and the 

 most of them were placed in one colony in a cold situation on the North Shore, where 

 the caterpillars were greatly retarded, and where there were still some in the first 

 stage. The remainder were colonized in warmer localities, where the caterpillars 

 were one stage farther advanced. 



Immediate success followed the planting of these colonies. Within three weeks 

 cocoons were found in each, and the number of parasitized caterpillars was gratify- 

 ingly large. A very careful investigation was conducted, to determine the proportion 

 which was attacked by native secondary parasites; and, while this was so large in one 

 instance as seriously to jeopardize the success of the experiment, it was not so large in 

 the others. 



There were several thousands of this first generation known to have developed in 

 the open upon American soil, which issued from the cocoons some four or five weeks 

 after the colonies were established, but in only that one on the North Shore, where the 

 caterpillars were in the first and second stages when the parasites were liberated, was 

 there a full second generation. Here the larger caterpillars were again, attacked, and 

 an abundant second generation of the parasite followed. 



Meanwhile, additional shipments of cocoons of the second Japanese generation were 

 received early enough to permit of a generation in the open upon the native cater- 

 pillars, and several other colonies were successfully established. It is known that 

 there were many thousands of the parasite issuing in at least five different localities 

 during August, but immediately thereafter they were completely lost to sight, and 

 it is futile to hope to recover traces of them before another spring. 



Until the late summer of 1909 nothing occurred to indicate that this parasite would 

 be likely to fly for any great distance from the point of its liberation; and, as has been 

 already stated, it was looked for in vain in the summer of 1909 in the immediate vicin- 

 ity of the colonies of the year before. In July, 1909, a strong colony was planted in an 

 isolated woodland colony of gipsy moths in the town of Milton. It was rather confi- 

 dently expected that it would attack these caterpillars so extensively as to destroy 

 the major portion; but it was the cause of some surprise, when the locality was visited 

 after the parasites of the new generation had mostly issued from the affected cater- 

 pillars, to find a smaller number of cocoons than there were individuals liberated in 

 the first place, and only about one-fourth, perhaps less, of the caterpillars attacked. 

 The circumstance was as discouraging as anything which had gone before, and for a 

 few days nothing happened to change its complexion. Then, to the intense surprise 

 of the writer, Mr. Charles W. Minott, field agent of the central division, sent to the 

 laboratory a bona fide example of the parasite, which had been collected in the Blue 

 Hills reservation, upwards of a mile away. There was no possible source except the 

 Milton colony, and a spread of upwards of a mile in something under a week was indi- 

 cated beyond dispute. At almost the same time the brood of Monodontomerus was 

 found for the first time in pupae of the gipsy moth in the field; and when the history of 

 this species is considered, in the connection which it bears toward the circumstances 

 surrounding the recoveiy of the Glyptapanteles so far from the point where it was 

 liberated, the whole situation is altered. 



Granted that the parasite disperses at the rate of one mile in each week of activity, 

 and that it is able to adapt its life and habits to the climate and conditions in America, 

 the chances are, that, instead of looking for it in the immediate vicinity of the points 

 of colonization, it is quite as likely to be found almost anywhere in the infested area 



