12 THE GIPSY MOTH AS A FOREST INSECT. 



At the same time the \vriter is averse to committing himself to the 

 extent of stating positively that the methods of forest management 

 to be suggested further on will invariably prove successful. He 

 wishes to emphasize the truth as he sees it, that the relative freedom 

 from injiny of certain types of forest is dependent upon the ''wait," 

 and that their continued well-being will largely depend upon the 

 persistence of this malady. 



lie wishes further to emphasize his belief that an increase in the 

 efficiency of the parasites will add to the variety of the forests which 

 may be cultivated to advantage, but that it will not result in pro- 

 tection to all the types which at present are to be found in the area 

 of infestation. The suggestion that experiments be conducted to 

 determine the practicability of the ''reserve-tree" method of culti- 

 A'ating oak is made oidy on the assumption that the parasites will 

 eventually render more efficient aid than at present and in a less 

 limited portion of the infested territory. 



In 1908 Mr. A. II. Kirkland, in his third annual rep(.)rt as superin- 

 tendent of work against the gipsy and brown-tail moths, first called 

 attention to the apparent resistance of white pine unless associated 

 with hardwood trees. A year later Mr. L. H. Worthley, his acting 

 successor, pidjlished in the next report the results of experiments 

 which showed that this was indeed the case, and that pure stands of 

 pine might be protected at a very reasonable expense. 



Partly in pursuance of this idea, and partly independently, Messrs. 

 D. M. Rogers and A. F. Burgess, of the Bureau of Entomology, after 

 observing the activities of the moth in the field, concluded that in 

 atldition to pine most of the other conifers, and certain hardwood trees 

 as well, might be considered as sufficiently resistant to escape serious 

 injury. Ash, hickory, and maple were mentioned, and recommenda- 

 tion was made jointly in Bulletin 87 of this bureau that such trees 

 be planted in place of those which were destroyed. 



These recommendations, made in 1910, were succeeded bv further 

 observations by employees of the Bureau of Entomology and the 

 Massachusetts State forester's office with the result that by the fall 

 of 1911 several important additions had been made to the list. 



Exact information, however, was lacldng, and because of the 

 obvious need for it a series of investigations was inaugurated under 

 the direction of Mr. Burgess. These were so planned as to demon- 

 strate not only what happened when caterpillai*s were confined to 

 certain sorts of food indoors, but exactly what happened following 

 invasion of different t3"pes of forest out of doors. More than 250 

 observation points were selected, representative of every type of pure 

 and mixed forest which could be easily located within the infested 

 area. In atldition. to pure stands of pine, oak, and birch, for example, 



