314 ENTOMOLOGICAL NEWS. [July, '14 



unfortunately I did not change the wording under the name 

 ditbitata. The specimen with which I compared dubitata has 

 only three distinct pairs of dorso-central bristles, hence my 

 locating it in front of dubitata. In other respects the descrip- 

 tion of the latter may be compared with that of setosa. 



I have to thank Dr. S. A. Forbes and Dr. E. P. Felt for per- 

 mission to publish the descriptions of the new species included 



in this paper. 



<> 



The Origin of Oligotropism (Hymen.)* 



By JOHN H. LOVELL, Waldoboro, Maine. 



Certain statements recently made by Mr. Robertson in re- 

 gard to the origin of oligotropism (Ent. News, 25: 67) call 

 for brief consideration. 



No evidence is offered to support his earlier assertion that 

 Epeolus is a parasitic genus. As regards Triepeolus donatus 

 the writer stated that he had taken it on the Compositae only 

 in this locality. 



Herman Miiller, notwithstanding his great experience as 

 a floroecologist, did not foresee the existence of the oligotropic 

 habit. A discovery in retrospect often offers little difficulty. 

 Thus Huxley writes: "My reflection when I first made my- 

 self master of the central idea of the 'Origin' was 'How ex- 

 tremely stupid not to have thought of that!' : (Life and Let- 

 ters, i : 183.) 



It is manifestly futile for Robertson to quote statements of 

 the writer, and merely express difference of opinion. This 

 mode of argument is not common in scientific papers. 



Robertson assumes the existence of competition. He says, 

 "My view is that the bee fauna is all that the flora will sup- 

 port." This I do not admit, on the contrary I believe that it 

 can be shown that only a part of the available flower food is 

 gathered by bees. The commonness of an insect species does 

 not depend alone on the quantity of food obtainable, e. g., oc- 

 casionally the forest caterpillar (Heterocampa guttivitta) , 

 which feeds on the leaves of deciduous trees, appears in count- 



