OF WASHINGTON. 207 



upon this good work, to do so without further delay, as much 

 good will result therefrom. 



Some years ago, in Insect Life (vol. II, p. 210), Mr. L. O. 

 Howard called attention to the European parasites bred from the 

 Gypsy Moth (Ocnerta dispar Linn.), an introduced European 

 pest now depredating places in Massachusetts, and for the exter 

 mination of which the Massachusetts legislature is spending an 

 nually thousands of dollars. Mr. Howard gave a list of no less 

 than 24 distinct species of Hymenoptera bred from it in Europe, 

 of which number 16 were primary parasites. It has always ap 

 peared to me singular why, with this knowledge before them, no 

 effort has ever been made, on the part of those in charge of the 

 work of destruction, to introduce some of these parasites. This 

 might have been done, some years ago, at a comparatively small 

 outlay between three or four thousand dollars at the most and 

 certainly, had this been done, the parasites would have aided 

 materially in the destruction of the pest and in keeping it within 

 reasonable bounds. 



In these introductory remarks I believe I have now said suf 

 ficient to demonstrate to you all the economic importance of these 

 parasites, and to impress upon you the benefits to be derived from 

 a thorough study of their habits and structure, although con 

 nected with them are many other problems of great biologic in 

 terest, upon which I would like to say a few words, but which 

 must be left unsaid for want of time ; and I will therefore leave 

 these untouched and proceed with the substance of my address 

 some important structural characters of these parasites. 



THE HEAD. 



The head has always been considered of great importance in 

 classification its size, shape, and various appendages entering 

 quite largely into all our systematic work, but it is not yet ex 

 hausted, and there are still important characters which may be 

 used by us in our work. 



On the accompanying Plate III, I have made some rough outline 

 figures of a few of the different shaped heads, in order to draw 

 special attention to some characters which should not be over 

 looked in classification, as they are frequently correlated with 

 other characters of primary importance. 



