OF THE LEPIDOPTERA
The Lepidoptera are divided into two very unequal groups, to which we have so frequently alluded as 'Butterflies' and 'Moths.' And, although these two terms are popularly applied in a fairly accurate manner, yet, strange to say, very few persons indeed have any definite knowledge of the differences that entomologists recognise between the two groups.
Every entomologist has his circle of sympathetic and, perhaps, even admiring friends. Consequently, many a little package is sent round to his abode 'with great care,' accompanied by a note or a message concerning the fine 'butterfly I have just caught, and thought you would like to add to your collection.'
The 'butterflies' that so frequently reach us through these channels nearly always turn out to be brightly coloured moths, and this naturally gives one the idea that the popular notion as to the classification of the Lepidoptera is based on colour or brilliancy of design, the term 'butterfly' being applied to the gayer species, and 'moth' to the more dingy members of the race.
There is really some shadow of a reason in this method of nomenclature, for butterflies are usually more brightly clad than moths; but the scientific classification, at least as far as the main divisions and subdivisions are concerned, has nothing whatever to do with colour or design; and we must at once acquaint ourselves with the fact that there are very dingy butterflies, and most beautiful and highly coloured moths.
How shall we account for the fact that the specimens so kindly sent us by our friends are generally moths? Is it because moths are more numerous and more frequently seen? They are certainly more numerous; for, while our butterflies do not number seventy species, the other division contains about two thousand. Yet, in spite of this fact, moths are not generally observed as much as butterflies, for the former are nearly all night-fliers, and the latter always fly by day and rest by night.
Still our question remains unanswered. The reason is this. The captives sent us are seldom caught on the wing. Most of our grown-up friends, even though they admire our own pluck and general carelessness concerning the remarks of the spectators of our entomological antics, would not themselves like to be seen, hat in hand, chasing a butterfly; and the night-flying moths are, of course, less frequently observed. But they often, in the course of their daily employments, meet with a large moth fast asleep in some corner of a dwelling house, workshop, or outhouse. Such moths are easily caught while in the midst of their slumbers, and, as they often make no attempt to fly by day, are as easily transferred to a box suitable for transmission by messenger or by post.
In the above few remarks we have alluded to some features by which the two great groups of the Lepidoptera may be distinguished; but we have already referred (page 5) to a far more important one in our description of the various forms of antennæ. All butterflies – at least all British butterflies – have knobbed or clubbed antennæ, while the corresponding organs of all our moths terminate in a sharp point.
This distinction obtains in all British Lepidoptera, and is so far regarded as the most important basis of classification that naturalists have derived from it the two Greek terms that are synonymous with our two popular names – butterflies and moths. The scientific name for the former group is Rhopalocera– a term derived from two Greek words, one signifying a horn, and the other a club, and thus meaning 'club-horned.' The corresponding name for moths is Heterocera, derived from the same source, and meaning 'variously horned.'
But, although we find embodied in these two long and formidable names an unerring mark of distinction between British butterflies and moths, we must not neglect other less important facts which, though less distinctive, are not without interest.
Observe a butterfly at rest. Its wings are turned vertically over its back, and brought so closely together that they often touch. In this position the 'upper' surfaces of the 'upper' wings are completely hidden from view, and the 'under' surfaces are exposed on the two sides, except that those of the 'upper' pair are partly hidden by the other pair.
Now look at a moth under the same circumstances, and you will generally find the wings lying over its body, which is almost or completely hidden beneath them. As a rule the upper pair together form a triangular figure, and entirely cover the second pair; but in some cases a portion of each of the under wings extends beyond the margin of those above them, and in others the upper pair extend so far forward that nearly the whole of the under wings is exposed behind them.
Fig. 37. – A Butterfly at Rest (Large Copper).
Fig. 38. – A Moth at Rest (Gothic).
Again, the wings of butterflies are so rigid that they can never be folded; but you will observe that the under wings of moths are generally very thin, soft, and pliant, and are neatly pleated lengthwise when not in use.
Another feature deserving notice is a slight difference to be often observed in the form of the body. The butterfly, which generally has a slender body, has a distinct constriction or waist between the thorax and abdomen. This is not so apparent with moths, and especially with the thick-bodied species.
The Rhopalocera or Butterflies are divided into Families, each of which contains insects that possess certain features in common by which they may all be distinguished from the members of any other family.
The British species represent eight families. They are as follows:
1. Papilionidæ.– Containing only one British species – the beautiful Swallow-tail (Plate I, fig. 1).
2. Pieridæ.– Containing ten species. These are often known collectively as the 'Whites,' but include four butterflies that are distinguished by beautiful shades of yellow and orange.
3. Nymphalidæ.– This family contains seventeen insects, among them being several splendid species. It includes the Fritillaries and Vanessas.
4. Apaturidæ.– Of this we have only one representative – the Purple Emperor (Plate V, fig. 1).
5. Satyridæ.– Including the 'Browns' and 'Heaths,' and numbering eleven species.
6. Lycænidæ.– Including the Hairstreaks, 'Coppers,' and 'Blues,' in all seventeen species.
7. Erycinidæ.– Containing only the 'Duke of Burgundy.'
8. Hesperiidæ.– This family contains seven British butterflies commonly known as the 'Skippers.'
Although all the members of the same family resemble each other in certain points of structure, or in their habits, yet we can often find among them a smaller group differing from all the others in one or two minor particulars. Such smaller groups are called Genera.
To make this all quite clear we will take an example.
The Brimstone Butterfly (Plate II, fig. 4) belongs to the second family —Pieridæ, all the members of which are distinguished from those of the other families by the characteristics mentioned on page 141.
But our Brimstone Butterfly possesses another very prominent feature in which it differs from all the other British Pieridæ, and that is the conspicuous projecting angles of both fore and hind wings. Among the foreign species of the family we are considering there are
