48 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



which are known to check its ravages over there . The insect was undoubtedly brought 

 over by Trouvelot without any of its natural checks. In my judgment it would be 

 well worth trying to import its parasites from abroad. The advantage would be this: 

 If you failed to exterminate it by spraying, its parasites, seeking for this particular 

 host, would be more apt to find the overlooked or escaped specimens than man would. 



No action was taken upon this suggestion, and the State author- 

 ities, believing that such an attempt would be useless owing to the 

 fact that their effort for some years was consistently devoted to the 

 aim of absolute extermination of the gipsy moth, perhaps wisely 

 saved the expense of a mission abroad for this purpose. Then, also, 

 there was some hope that the native parasites, particularly the ich- 

 neumon flies and the native species of Apanteles, .as well as tachina 

 flies and some of the carabid beetles, might gradually accommodate 

 themselves to the imported pest and prove prominent factors in the 

 fight against it. 



This last faint hope, however, was not justified. In the course of 

 the careful work done by the State during the next seven or eight 

 years, the better part of which is summarized in the admirable Report 

 on the Gipsy Moth, by Forbush and Fernald, published in 1896, sev- 

 eral native parasites and predatory insects were observed to attack 

 the gipsy moth in its different stages, but at no time was the per- 

 centage of parasitism sufficiently great to have any value as a factor 

 in the suppression of the pest. At no time was there a greater per- 

 centage of parasitism by native parasites than 10, whereas the con- 

 dition in Europe is such that the percentage reaches frequently well 

 above 80. It may be worth mentioning that parasitism by native 

 species has never exceeded 5 per cent in any collections made since the 

 present laboratory was established. It is nearer 2 per cent on the 

 average. 



In discussions among the Washington entomologists it was repeat- 

 edly pointed out by E. A. Schwarz and by B. E. Fernow (at that time 

 Chief of the Division of Forestry of the United States Department of 

 Agriculture) that one of the most important of European enemies of 

 the gipsy moth, and the nun moth as well, is one of the tree-climbing 

 ground beetles known as Calosoma sycophanta L. There exist a num- 

 ber of species of this same genus Calosoma in the United States, but 

 none of them has the tree-climbing habit developed to the same ex- 

 tent as have Calosoma sycophanta of Europe and its relative Calosoma 

 inquisitor L. Prof. Fernald, writing to the famous German authority 

 on forest insects, Dr. Bernard Altum, early in 1895, asked his opinion 

 as to the advisability of importing these tree-inhabiting ground beetles, 

 but received the reply that such an importation would not give good 

 results. Prof. Altum considered the services of the hymenopterous 

 parasites of the old genus Microgaster as of much more importance. 



In the report just cited Fernald disposed of the question of import- 

 ing parasites in the following words: 



