196 THE CANADIAN ENTOMOLOGIST 



The sections on "Studies in the Parasitism of Native Insects" 

 and "Parasitism as a Factor in Insect Control" are particularly 

 interesting. To attempt, however, to pick out the most interest- 

 ing and valuable portions of the work would be fruitless, as there 

 is scarcely a paragraph that is not well worth reading. 



A limited supply of the Bulletin was distributed in July, 1911. 

 A general distribution has, however, only recently been made. 



Since its publication a short article on "The Gipsy Moth as a 

 Forest Insect," by the junior author, has appeared as Circular 

 No. 164, U.S. Bureau of Ent. Speaking of the results of parasite 

 importation, Mr. F'iske says: "On the whole, the results are de- 

 cidedly satisfying, and the State of Massachusetts and the United 

 States Department of Agriculture have no cause to regret having 

 undertaken the unexpectedly formidable task of parasite importa- 

 tion. Within a territory entering a little to the northward of 

 Boston, it may be conservatively stated that fully 50 per cent, of 

 the eggs, caterpillars, or pupa^ of the Gipsy Moth, in the aggregate, 

 were destroyed by imported parasites in 1912." It is Mr. Fiske's 

 opinion that this present rate of mortality in the central portion of 

 the infested territory will eventually be considerably increased 

 and will extend itself over the entire area of infectation. 



In speaking of the amount of additional control necessary to 

 check the increase of the Gipsy Moth in America, it is stated in 

 Bull 91, p. 117, 1. 11, that "An aggregate parasitism of 85% will 

 almost certainly be sufficient, and it may well be that 80%, or even 

 75%, will answer equally well. Much less than 75% will probabh' 

 not be effective." 



In conclusion, it may be said that the Bulletin contains a 

 wealth of information on a subject that has hitherto been little 

 understood. It treats of a strictly scientific subject in a scientific 

 way, and has the merit of being written in a particularly attractive 

 style. It will be indispensable to any entomologist interested in 

 natural control of insects. The excellent illustrations, of which 

 the majority are original, materially enhance the permanent value 

 of the work. J- F)- Tothill. 



Mailed June 7th, 1913. 



