NORTH AMERICAN EUCOSMINAE. 11 



species are of prime economic importance and four of our common 

 introduced pests {Spilo7iota ocellana, Grocidosema pleheiana^ Rhopo- 

 hota 7iaeva7ia, and Rhyacionia huoliana) are members of the subfam- 

 ily. In fact the species constituting the genera Rhyacionia, Petrova, 

 and Barbara (the old genus Evetria of authors) are the most impor- 

 tant lepidopterous enemies of our coniferous trees. Nearly every 

 plant family finds an enemy somewhere in the Eucosminae and its 

 range of food plants covers most of the genera of our flora. All 

 authentic food plant records are given under each species. It is 

 hoped that the too frequent phrase, " food plant unknown ", will 

 stimulate more extensive biological activities; for only when the 

 larvae of our species are known will it be possible to construct a truly 

 satisfactory taxonomy. 



KEY TO THE GENERA OF EUCOSMINAE. 



The genus Hendecaneura Walsingham, treated in the appendix, is not included in this 

 key. It would fall under No. 24 and be differentiated from Zeiraphera by the "stalked 

 rather than approximate condition of veins 6-7 in the hind wing. 



1. Fore wing with a distinct notch in termen ; hind wing with veins 3 and 4 



connate (18) Gwendolina. 



Fore wing with or without a notch ; but if notch is present veins 3 

 and 4 of hind wings never connate 2 



2. Fore wing with apex falcate 3 



Fore wing with apex pointed or rounded but not distinctly falcate 4 



3. Veins 3 and 4 of hind wings stalked '. (25) Ancylis. 



Veins 3 and 4 of hind wings united (24) Anchylopera. 



4. Fore wing with 4-5 connate 5 



Fore wing with 4-5 separate or approximate ; not connate 7 



5. Costal hook of harpe absent; socii rudimentary or absent— (2) Rhyacionia. 

 Costal hook of harpe present ; socii developed, long 6 



6. Harpe with rudimentary clasper (3) Petrova. 



Harpe without such clasper (4) Barbara. 



7. Fore wing with 7 and 8 united 8 



Fore wing with 7 and 8 approximate connate or stalked 10 



8. Uncus absent ; if rudimentary not bifurcate 9 



Uncus weak but developed, bifurcate (21) Kimdrya, 



9. Veins 3 and 4 of hind wing stalked ^ (11) Sonia. 



Veins 3 and 4 of hind wing united (10) Suleima. 



to. Antenna of male with notch above basal joint 11 



Antenna of male without notch above basal joint 12 



11. Fore wing smooth (5) Spilonota. 



Fore wing with tufts of raised scales above dorsum (6) Stepsicrates. 



12. Harpe with heavy spines from outer surface 13 



Harpe without heavy spines from outer surface 15 



13. Gnathos and socii fused; socii caudally projected (22) Rhopobota. 



Gnathos and socii separate; socii drooping 14 



14. Fore wing with tufts of raised scales above dorsum (13) Proteoteras. 



Fore wing smooth (19) Crocidosema. 



15. Eighth abdominal segment modified and included in genitalia 16 



Eighth abdominal segment not so modified 17 



