14 IOWA STUDIES IN NATURAL HISTORY 



or nine veins, five usually absent ; cell open. Two anals. Front 

 legs normal, tibiae usually with the epiphysis present (in all 

 North American genera). Middle legs with: one pair of spurs 

 on the tibiae and with or without spines. Hind legs with two 

 pairs of spurs, or with only the distal pair in some genera. 

 The two families are based on the following characters: 

 Family HESPERIIDAE : Head nearly as wide to wider than 

 thorax. Hind tibiae usually with two pairs of spurs. Pal- 

 pi moderate to large. Larvae external plant feeders. 

 Family MEGATHYMIDAE : Head narrower than thorax. 

 Hind tibiae with one pair of spurs. Palpi rather small. 

 Larvae borers in plant stems. Imagines larger than most 

 Hesperiidae, heavy bodied and strong of flight. 



Family HESPERIIDAE 

 Characters of the superfamily, distinguished from the Me- 

 gatJiynvidae as shown in the preceding synopsis. The North 

 American species fall into three subfamilies which may be sep- 

 arated by the following key, which also deals with the groups 

 into which the subfamilies are divided. 



Key to subfamilies and groups 



1. Club of antennae large, entirely reflexed. . . . pybrhopyginae 

 Club variable, never entirely reflexed 2 



2. Vein 5 of primaries not curved at base, usually about inter- 

 mediate between 4 and 6. Mid tibiae without spines 



HESPERIINAE 3 



Vein 5 curved at base, arising nearer to 4, or with the mid 

 tibiae spined pamphilinae 4 



3. Cell of primaries more than two-thirds as long as wing or 

 antennae with a slender reflexed or recurved apiclus 



Group A 



Cell two-thirds or less. Club curved, blunt or fusiform, but 

 never with a slender apiculus Group B 



4. Vein 5 intermediate, straight. Club blunt. Palpi porrect 



Group A 



Vein 5 curved at base, nearer to 4. Palpi not porreclt. 

 Group B of authors 5 



