FOREST INSECTS 77 



caterpillars. One disease is now very prevalent, and attempts 

 are being made with good prospect of success to introduce 

 another one which occurs in Japan. Also a large predatory 

 European beetle {Calosoma sycophanta) (Fig. 36) which feeds 

 upon the caterpillars has been liberated in America, and has 

 multiplied with astonishing rapidity. 



This method of control is i)articnlarly adaptable to forest 

 insects, since the princi])le of annual rotation as applied to 



Fig. 36. Calosoma sycophanta, a Euro- 

 pean beetle introduced into the L'nited 

 States to combat the gipsy moth. Both 

 the larval and adult beetles feed upon the 

 caterpillars of the moth. 



agricultural crops is impossible in the case of trees, and al- 

 though long term rotation is possible, it does not bear the 

 same relation to insect abundance. Spraying also is un- 

 profitable, and not at all practicable except under exceptional 

 circumstances. It appears, therefore, that control of forest 

 insects cannot be undertaken along as many lines as that of 

 agricultural insects, and from this point of view at least, 

 forest insects present much the more difficult problem. 



The relation of parasites to the abundance of the gipsy 

 moth in America cannot, of course, be regarded as entirely 

 similar to that existing in Europe where the moth is native, 

 and an inquiry into the parasitic control of this moth in its 

 native home, or of any of our native insects will reveal much 



