16 



been since. Not only have the English sparrows (which, by the way, 

 feed but rarely upon the gipsy moth) driven away many of the other 

 birds, but pot-hunters from Boston and from the manufacturing towns 

 about Boston, especiallj" persons of foreign birth, have destroyed 

 great numbers of insectivorous birds. The caterpillars are prej^ed 

 upon by the cuckoos, the Baltimore oriole, the yellow-throated vireo, 

 and the blue jay. The moths, when they emerge, are eaten bj^ many 

 birds, and the eggs are eaten by several species. 



Certain of our native parasites which destro}^ allied insects like the 

 fall webworm and the tussock moth also breed in the gipsj' moth cater- 

 pillar and chrysalis. A number of species were bred during the early 

 Massachusetts State work, but the percentage of parasitism was very 

 small. 



An effort is being made by the Bureau of Entomology, in coopera- 

 tion with the Massachusetts State authorities, to introduce the Euro- 

 pean parasites of the gipsy moth, and of the brown-tail moth as well, 

 and during the past year many thousands of such parasites have been 

 introduced and liberated in the vicinity of Boston. They are first 

 cared for in a laboratory at North Saugus; many of them are after- 

 wards studied under out-of-door tents, while still others have been 

 liberated in the open and badly infested woodlands, such locations for 

 liberation having been chosen as are likelj' to remain undisturbed 

 either by insecticidal operations or b}^ forest fires. The results so far 

 are encouraging, but it may be, and probably will be, several years 

 before appreciable results will be obtained, and it may be that these 

 European parasites will not increase as rapidly or do as good work as 

 the}'- are known to do in Europe. In the Old World, as has been pre- 

 viously indicated, the gipsy moth is only occasionally present in suflS- 

 cient numbers to do noteworthy damage, and it is ordinarily kept in 

 check by its parasites and other natural enemies. In this country, 

 therefore, active mechanical measures must still be continued, and 

 perhaps for years to come, in the actual destruction of the injurious 

 insect before relief from parasites is gained. 



REMEDIES. 



The gipsy moth, when occurring in moderate numbers, is not at all 

 a difficult insect to fight. When young the caterpillars are readily 

 killed by spraying the trees with the ordinary arsenical poisons. As 

 they grow older they develop a remarkable resistance to the action of 

 arsenic, so that stronger and stronger proportions must be used. It was 

 early found that Paris green and London purple can not be used effec- 

 tively against well-grown larvas unless the proportion of the arsenical 

 to the amount of water is so great as to burn the foliage of the trees or 



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