3. Body with two or more horns or enlarged tubercles (scoli) ……….4
Body with single horn (or scar from loss)….6
5. Ninth abdominal segment lacking single dorsal horn;anal plate smooth…..SATURNIIDAE
Ninth abdominal segment with middorsal horn or scolus:anal plate with small spines….. SATURNIIDAE
6. Abdominal segments with six to eight annulets ….SPHINGIDAE
Abdominal segments with three or less annulets ……BOMBYCIDAE
8. Body with many long setae ….9
Body with either obscure short setae or few long setae…..13
10. Eversible middorsal glands on sixth and seventh abdominal segments; dense brush of setae on several abdominal segments……LYMANTRIIDAE
Not as above …..11
12. Body setae usually plumose…..NOCTUIDAE
Body setac usually not plumose…..ARCTIIDAE
13. Fleshy filaments on mesothorax and usually on eighth abdominal segment …..DANAIDAE
Fleshly flaments absent on mesothorax and on eighth abdominal segment DANAIDAE ….14
15. Prolegs absent or vestigial on fifth abdominal segment…GEOMETRIDAE
Prolegs present on fifth abdominal segment….NOCTUIDA