The term Rhopalocera, as applied exclusively to the butterflies, is a mere convenience, and does not (as has been falsely stated by some lepidopterists) express any constant distinction between butterflies and moths; indeed, these groups are only to be distinguished by family characters, such as the structure and habits of the larvæ, the form and economy of the pupæ, and the habits, form of venation, or other structural peculiarities of the imago; the same characters do not hold good as distinctive marks throughout the moths, and thus it happens that some genera are in a wretcted state of “limbo,” neither accepted as butterflies by the student of that group, nor permitted to rest peacefully among the moths.
Butterflies therefore are not all “club-horned,” some have clubs, some have filiform antennæ, some have moniliform and subserrated antennæ. In the Hesperiidœ alone you have any amount of variation of structure—clubs, hooks, whips, spoons; all indicating a mere generic distinction and not differing from the same organs in such families as the Sphingidœ, Carteriidœ, and Agaristidœ. The term Rhopalocera therefore is used to indicate the five highest families of the Lepidoptera—the Nymphalidœ, the Erycinidœ, the Lycœnidœ, the Papilionidœ, and the Hesperiidœ.
As the entomologists of Australia and New Zealand do not seem thoroughly to comprehend why the Nymphalidœ (and not the Papilionidœ) are now placed at the head of the butterflies, we shall here quote from Mr. Bates's admirable paper in the Journal of Entomology for 1864, and they will then see that this renowned lepidopterist has arranged the five families in a perfectly gradational and natural series. He has not followed Linnæus in choosing the Papilionidœ to commence with because they are big, and the Hesperiidœ to conclude with because they are little, but he has studied the structure of each family from the larval to the perfect condition.*
“Family 1. Nymphalidæ. Front legs imperfect in both sexes; in the female wanting the tarsal claws; in the male the fore tarsi quite rudimentary, consisting of one or two spineless joints. Pupa suspended freely by the tail.
a. Lower disco-cellular nervule of the hind wing perfect.
Subfamily 1. Danainœ. Larvæ smooth, with fleshy processes. Fore-wing submedian nervure of the imago double at its origin. (This subfamily includes the greater part of the Heliconidœ of authors).
Subfamily 2. Satyrinœ. Larvæ with bifid tails, spineless. Palpi of the imago generally compressed and fringed with long hair-scales.
Subfamily 3. Brassolinœ. Larvæ generally with bifid tails, spineless. Hind wing of the imago furnished with a prediscoidal cell.
Subfamily 4. Acrœinœ. Larvæ studded with branched spines. Palpi of the imago thick and scantily clothed with hair.
Subfamily 5. Heliconinœ. Larvæ studded with branched spines. Palpi of the imago clothed with fine scales, and hairy in front.
b. Lower discocellular nervule, at least of the hind wing, more or less atrophied.
Subfamily 6. Nymphalinœ.
Family 2. Erycinidæ. Six perfect legs in female; four in male; the anterior tarsi consisting only of one or two joints and spineless.
Subfamily 1. Libythœin. Pupa suspended freely by the tail.
Subfamily 2. Stalachtinœ. Pupa secured rigidly by the tail in an in-clined position without girdle.
Subfamily 3. Erycininœ. Pupa recumbent on a leaf or other object, and secured by the tail and a girdle across the middle.
Family 3. Lycænidæ. Six perfect legs in female; four in male; the anterior tarsi wanting one or both of the tarsal claws, but densely spined beneath. Pupa secured by the tail and a girdle across the middle.
Family 4. Papilionidæ. Six perfect legs in both sexes. Pupa secured
[Footnote] * Compare Scudder “On the Classification of Butterflies,” Trans. Am. Ent. Soc., 1877, pp. 69–80.
by the tail and a girdle across the middle. (The true Papiliones have a leaf-like appendage to the fore tibiæ—a character which approximates the family to the Hesperidœ and moths.
Subfamily 1. Pierinœ. Abdominal margin of the hind wing not curved inwards.
Subfamily 2. Papilioninœ. Abdominal margin of the hind wing curving inwards.
Family 5. Hesperidæ. Six perfect legs in both sexes; hind tibiæ, with few exceptions, having two pairs of spurs. Pupa secured by many threads, or enclosed in a slight cocoon.”*
Excepting that a few sub-families have been added, this arrangement remains in its entirety, and is the basis of the classification adopted by all the rising generation of European lepidopterists.
The butterflies of New Zealand are at present restricted to three of the five families—Nymphalidœ, Lycœnidœ, and Papilionidœ.
[Footnote] * Journal of Entomology, No. X., pp. 176–7 (1864).