23 



(8) Monodontomerus aereus, a Chalcid, as already mentioned, 

 is a parasite of the pupa of the Brown-tail as well as the Gipsy. 



(9) Pimpla instigator, an Ichneumon, was introduced from 

 Europe, but has not been recovered from the field. 



Among the native parasites of the Brown-tail in America are: - 



Trichogramma poretiosa, a chalcid egg parasite, 



Anomalon exile, a caterpillar parasite, 



Theronia fulvescens, an Ichneumon, 



Pimpla conquisitor, on pupae, 



Chalcis compsilurae, on cocoons, 

 but as already stated, the control is inadequate. 



CONCIvUSION. 



The task of importing the foreign parasites, of the Gipsy and the 

 Brow^n-tail moths to the United States has been a most arduous and diffi- 

 cult one. In the first place it involved much labor in getting competent 

 collectors in Kurope to gather sufficient parasitized material, for, as I 

 have already stated, t|he plan of the utilization of foreign parasites on a 

 large scale in the control of injurious forms is recent in conception, and 

 was put into operation for the first time by the U.S. Bureau of Entomo- 

 logy in the fight against the Gipsy and the Brown-tail Moths. In the 

 second place, many difficulties in transportation had to be overcome. In 

 the third place, the v^'^ork of sorting out the various parasites and herd- 

 ing them in sufficientlv large numbers in the laboratories for colonization 

 purposes in the field was much greater than was anticipated at the out- 

 set. In the fourth place, the habits of many of the parasites were not 

 well known, and had to be determined for American conditions. As a re- 

 sult, many of the parasites reported favorably in Europe were found to 

 be secondary parasites, or unsuited for the task in hand. 



While we must admit that the importation of the foreign parasites 

 of the Gipsy and the Brown-tail M ths has been successful, we should 

 not conclude that these pests are now under control. It will take sever- 

 al vears for the parasites to spread to the limits of the infested areas, 

 and in the meantime the pests will go on spreading unless other mea- 

 sures are taken to check them. Much can be done to hasten the spjread 

 of the parasites by artificial colonization, as is being done at Frederic- 

 ton, N.B. by Mr. Tothill, as agent of the Division of Entomology at Ot- 

 tawa. The fight is by no means over; the pests must be fought "by artifi- 

 cial means until the parasites are sufficiently abundant to destroy 85 to 

 90 per cent of them. 



The improvement in Massachusetts "is due to at least four main caus- 

 es: ( I ) the perfection and standardization of the methods for artificial 

 repression; ( 2 ) the death of a large proportion of the more susceptible 

 trees or their removal from the infested woodlands; (3,) the importation 

 of parasitic and predatory insect enemies; and ( 4 ) the development of 

 the "wilt" disease" (Fiske). 



