INSTITUTE, PUSA, FOR 1917-18 89 



larval and pupal stages, these differences being most easily 

 appreciable in the pupae as a rule. As regards the adults, 

 except in a few cases, the types of coloration and pattern of 

 markings are very uniform in all the species, and it is 

 extremely difficult to distinguish these or to make the 

 minute distinctions between them easily apparent by 

 description or figures ; study of the male genitalia has, how- 

 ever, indicated that the differences found in the immature 

 stages correspond with differences in these structures, and 

 further study of more ample material will doubtless enable 

 us to differentiate between the adults, a thing which we are 

 unable to do at present with any real satisfaction. 



The nomenclature of these various forms is at present 

 in such a state of confusion that it seems inadvisable to 

 apply any names at all pending a thorough systematic revi- 

 sion of the whole of this group. Many of the species now 

 discriminated are probably undescribed, and the applica- 

 tion of the names in the eases of those species of which 

 descriptions have been published is extremely doubtful in 

 most cases. In last year's Report, for example, I referred 

 to a species under the name of Diatrcea suppressalis (auri- 

 cilia), quoting auricilia, Ddgn., as synonymous with 

 suppressalis, Wlk., on the authority of Sir George Hampsoi 

 (Bombay N. H. S. Journal, XXI, 1250); further examina- 

 tion, however, shows that our cane-borer, which is appar- 

 ently identical with auricilia (specimens of which, named 

 by Dudgeon himself, are in the Pusa and Indian Museum 

 collections), is quite distinct from examples agreeing exactly 

 with the " Fauna " description of suppressalis, which latter 

 species we have not bred as yet either from cane or any 

 allied plant and whose early stages are as yet unknown to 

 us although it is sufficiently common at Pusa.- It may also 

 be queried whether Diatrcea striatalis, described by Snellen 

 from Java, is truly synonymous with venosata, Wlk., from 

 Sarawak. It seems better, therefore, to refer to these 

 different species at present simply under the numbers of the 

 Cage-slips under which they have been reared at Pusa, leav- 

 ing to the future the allocation of exact specific names. 



* Q 



