60. Hind wing with nervule 8 coincident with 7 .......... Fam. 13. Sesiidae, see p. [386].
61. Hind wing with nervule 8 free (Cat. 62, 63).
62. Fore wing with nervure 1b simple or with a very minute fork at base .......... Fam. 14. Tinaegeriidae, see p. [387].
63. Fore wing with nervure 1a forming a large fork with 1b at base .......... Fam. 45. Tineidae, see p. [428].
64. Wings divided into plumes (Cat. 65, 66).
65. Fore wing divided into at most two, hind wing into three plumes .......... Fam. 42. Pterophoridae, see p. [426].
66. Fore wing and hind wing each divided into three plumes .......... Fam. 43. Alucitidae (= Orneodidae), see p. [426].
Fam. 1. Castniidae.—The Insects of this family combine to a large extent the characters of butterflies and moths. The antennae are knobbed or hooked at the tip, there is a large precostal area to the hind wing. The nervules of the front wing are complex and anastomose so as to form one or more accessory cells (Fig. 162). This important, but not extensive, family consists chiefly of forms found in tropical America and Australia. The diversity of size, form and appearance is very great, and it is probable that the members of the family will be separated; indeed, taxonomists are by no means in agreement as to the limits of the family. The Castniidae are diurnal Insects, and the North American genus Megathymus is by many considered to belong to the Rhopalocera. Euschemon rafflesiae (Fig. 186) is extremely like a large Skipper with long antennae, but has a well-marked frenulum. The members of the Australian genus Synemon are much smaller, but they also look like Skippers. Their habits are very like those of the Hesperiidae; they flit about in the hot sunshine, and when settling after their brief flights, the fore wings are spread out at right angles to the body, so as to display the more gaily coloured hind wings; at night, or in cloudy weather, the Insect rests on blades of grass with the wings erect, meeting vertically over the back, like a butterfly. Hecatesia, another Australian genus, is now usually assigned to Agaristidae; its members look like moths. The male of H. fenestrata is provided with a sound-producing organ similar to that of the Agaristid genus Aegocera.
Fig. 186—Euschemon rafflesiae. Australia. (After Doubleday.)