36 



THE EEPOKT OF THE 



Xo. 36 



ill the wall of its mid-intestine. This it was enabled to do by reason of a piercing 

 ovipositor, beautifully adapted for ^ the purpose. Moreover, this fly was found 

 to be one of the chief factors in the natural control of the brown-tail and gipsy 

 moths in Europe. 



With characteristic energy the United States Government, through Messrs. 

 Howard, Fiske, Townsend and Burgess, took steps to introduce this parasite into 

 the New England States where the gipsy and brown-tail moths were creating 

 such havoc. The story has been told of the collection in Europe of thousands of 

 these parasites and of their liberation in Massachusetts, and of how after several 

 years of anxious waiting the species was finally recovered and known to be breeding 

 on American soil. It has also been related that with almost incredible swiftness 

 the fly increased in numbers so as to take its place in the American fauna as 

 one of the most potent factors in the control of the two insects it was expected to 

 attack. 



Fig. 2. — ^Compsilura adult. This 

 excellent parasite of the 

 Gipsy and Brown-tail Moths 

 is now established in Canada. 

 (After the U.S. Bureau of 

 Entomology.) 



When the brown-tail moth spread into Canada the country was confronted 

 with a situation demanding immediate action, and the Dominion Entomologist 

 arranged not only for a field campaign against the invader but also for the intro- 

 duction from Massachusetts of its natural enemies. 



The question of what to introduce into the Canadian brown-tail moth area 

 had to be thought over very carefully, because it was realized from tlie iirst tliat 

 our Canadian problem differed in important respects from the New England one. 

 The fine beetle Calosoma was available and was colonized rather as a safeguard 

 against a possible outbreak of the gipsy moth than in the hope of its being 

 of immediate assistance in our brown-tail moth situation ; for like most 

 ])redacious animals it can increase only when the food supply is abundant. Aii 

 Apanteles which was available had done fairly good work in Massachusetts and 

 was also brought across the international boundary in the hope that it might 

 live in our more rigorous climate and be of equal usefulness. The insect, however, 

 that seemed to warrant almost any amount of effort to introduce was our little 

 friend Compsihira. 



We needed a parasite that could live upon native hosts as well as on our 



