2 U.S. NATIONAL MUSEUM BULLETIN 244 



or a few specimens. (Undoubtedly this lack of adult specimens 

 results in part from the exceedingly brief period of the year during 

 which these forms may be collected.) 



4. The disappearance or unavailability of the type specimens, a 

 fact that is all too frequently linked with the inadequacy of the 

 original description in providing diagnostic characters that can be 

 relied upon. 



5. The lack of biological data, a factor which can be of prime im- 

 portance in a group that displays so much structural homogeneity. 

 (This paucity in large part may be due to the extended life cycle of 

 the larva, a factor which hinders breeding and rearing experiments.) 



6. The lack of adequate collecting data, involving not only locality 

 (especially for types) but also the association of larval cases with 

 their corresponding adult, a fact of paramount importance in no. 7. 



7. The erection of new species solely on the larval case or on the 

 basis of a few general statements concerning the larva and/or pupa. 



8. The polyphagous feeding habit of the larva. (This sometimes 

 facilitates the rearing of these insects but of course makes it impossible 

 to interpret precise relationships based on host preferences.) 



9. The possibility of hybridization between certain species. (Suffi- 

 cient evidence is at present lacking to support this supposition.) 



Taxonomic keys and discussions of the larvae were omitted because 

 immature stages of only a few species were available. A preliminary 

 exammation of setal maps, noting color markings and variations, etc., 

 revealed only a few minor divergences among some of the species; 

 thus, it is believed that larval systematics will not profoundly modify 

 the present classification, which is based essentially on the adult male. 



Future work should be concerned especially with the collecting of 

 all stages of these insects. This work could best be done through 

 rearings, a procedure that would provide not only an abundant series 

 of specimens representing all stages but also would furnish material 

 that definitely could be associated. Genetic information obtained 

 from attempts to cross certain species and populations may be 

 difficult to acquire but would be highly desirable. 



All the specimens used in this study were borrowed from 

 the collections of the United States National Museum, the British 

 Museum, and the sources Hsted below. The abbreviations used to 

 indicate where the material is deposited are: 



AMNH — American Museum of Natural History, New York, N.Y. 

 ANS — Academy of Natural Sciences, Philadelphia, Pennsylvania. 

 BM — British Museum (Natural History), London, England. 

 CAS — California Academy of Sciences, San Francisco, California. 

 CM — Carnegie Museum, Pittsburgh, Pennsylvania. 

 CNC— Canadian National Collections, Ottawa, Ontario. 

 CPK — Collection of Charles P. Kimball, Sarasota, Florida. 



