The Moths of the British Isles Volume I Part 1

The Moths of the British Isles.

by Richard South.

PREFACE.

Compared with our b.u.t.terflies, the number of moths found in the British Isles is very large. Like the b.u.t.terflies, moths too are dependent upon plant life, and almost every kind of herb, bush, or tree, will be found to nourish the caterpillars of one or more species of moth.

Not only the field botanist, but every rambler in the country must constantly come across moths or caterpillars that will probably interest him, and of which he would be glad to learn something about their habits, life-history, and the position they occupy in the arrangement and cla.s.sification of Natural History objects.

In the preparation of this little book on our moths, the author has proceeded closely on the lines adopted when dealing with the b.u.t.terflies in his previous volume. That is, the chief aim has been to place before the nature lovers as much information concerning these creatures as could be condensed into moderate limits.

Lengthy descriptions were out of the question, but what might be considered an omission in this way, is amply compensated for by the life-like portraits of typical examples of the moths themselves, and in many cases of their more important varieties. Technicalities have been avoided as far as possible, the main object being to provide a guide to the identification of our moths, together with a simple account of the whole or a part of their earlier stages.

The author is fully aware that this method of treatment only enables him to touch the fringe of the subject, as it were, but he has been content to deal with it in this way, as it appeared to be the kind of information that would most nearly meet the requirements of the majority.

The author desires here to express his thanks to Mr. Robert Adkin, F.E.S., for the loan of specimens of _L. coenosa_, _E. ilicifolia_, _D. harpagula_, _N. albula_, _N. centonalis_, _D. barrettii_, _D. caesia_, _P. xanthomista_, _T. extrema_, _L. favicolor_, _L. vitellina_, and _H. pal.u.s.tris_. To Mr.

Alfred Sich, F.E.S., for the use of drawings of the caterpillars of _D.

tiliae_, _S. f.a.gi_, _L. bicoloria_, _P. ridens_, _A. auricoma_, _A.

rumicis_, _A. aceris_, _N. brunnea_, _M. oleracea_, _A. tragopogonis_, _T.

gothica_, and _T. incerta_. To Mr. H. L. Sich for the loan of drawings of the caterpillars of _D. euphorbiae_, _D. galii_, _D. chaonia_, and _P.

dictoea_. For the material figured on Plate 148, except the larva of _L.

putrescens_, kindly sent by Mr. Walker, of Torquay, he is indebted to Mr.

H. M. Edelsten, F.E.S.

Except where otherwise mentioned, the ill.u.s.trations of moths and caterpillars at rest are from photographs by "A Forester."

To Mr. Horace Knight he is very greatly obliged for the care bestowed upon the drawings of ova, larvae, and pupae, the bulk of which were made from living examples; also the coloured drawings for Plates 1, 45, 63, 68, 73, 75, 80, 84, 90, 108, 119, 123, 140, 146, 149, and 153. The only figures copied from any previous publication are those of the caterpillars of _S.

fuliginosa_, _D. sanio_, _D. pulch.e.l.la_, _A. corticea_, _A. strigula_, _N.

plecta_, and _N. augur_ (Wilson's "Larvae Brit. Lep."); and among the moths, the varieties of _A. caia_; _D. mendica_ (4 Yorks.), Trans. Ent. Soc.

Lond., 1889; _S. walkeri_, Curtis, and _N. subrosea_, Stephens.

RICHARD SOUTH.

THE MOTHS OF THE BRITISH ISLES.

PART I.

INTRODUCTORY.

As mentioned in "b.u.t.terflies of the British Isles," there is, speaking generally, no clear line of division between moths and b.u.t.terflies, and, as Dr. Sharp, in "Insects," puts the case, "the only definition that can be given of Heterocera [moths] is the practical one that all Lepidoptera that are not b.u.t.terflies are Heterocera." Now, it happens that all the b.u.t.terflies occurring in these islands have the tips of the horns (_antennae_) clubbed; and, although there is much variety in the structure of the horns of our moths, none of them have the tips k.n.o.bbed.

Like the b.u.t.terflies, moths pa.s.s through the stages of egg, caterpillar, and chrysalis before they attain the perfect state (_imago_), and the duration of the several stages is just as variable. The majority a.s.sume the moth condition but once in the year, but some species have two, or even three, generations in the twelve months, whilst others occupy twenty-four months in completing the life cycle. In one or two species the chrysalis stage may last four, five, or even six years.

Diversity of form and structure is considerable in the early stages as well as in the perfect insects, and this is shown in the {2} selection of life-history details figured on the black and white plates in this volume.

[Ill.u.s.tration: FIG. 1.

CONVOLVULUS HAWK-MOTH AND FLOWER OF NICOTIANA.

(Photos by W. J. Lucas.)]

Except that it is generally less prominent, the head, with the various parts thereof, is pretty much the same as in the b.u.t.terflies. In a few families, however, the "tongue" (proboscis) is only rudimentary or even entirely absent; while in others it is very long. The Convolvulus Hawk-moth has the proboscis of such length that it is able to reach the deep-seated nectary of such tubular flowers as those of _Nicotiana affinis_. In the ill.u.s.tration the "tongue" of the moth and the sweet-scented tobacco blossom are shown on exactly the same scale.

Fig. 2 represents some forms of antennae found in moths. A, {3} thickened and spreading out towards the tip (_dilate_); B, simple, thread-like (_filiform_) structure, without teeth, hairs, or bristles; C, fringed with fine hairs (_ciliate_); D, fringed with fine hairs, and with longer bristles at the joints (_setose ciliate_); E, the fringe in tufts (_fasciculate_); F, toothed, with fine hairs on the teeth (_dentate ciliate_); G, toothed with hairs in tufts from the teeth (_dentate fasciculate_); H, I, with double rows of hair scales (_bipectinate_); in I the projections are continued to the tip, and are themselves fringed with fine hairs, giving the antennae a very feather-like appearance--the term "plumose" is sometimes used to describe this form of antennae; in H the pectinations do not reach the apical fourth, which is simple. J, the _lamellate_, that is, the undersides of the rings or joints are made up of minute plates.

[Ill.u.s.tration: FIG. 2.

ANTENNae OF MOTHS.]

[Ill.u.s.tration: FIG 3.

CONNECTING BRISTLE AND CATCH.]

The wings of a moth are practically identical with those of a b.u.t.terfly (see diagram "b.u.t.terflies of the British Isles," p. 12). Normally the fore wings have twelve ribs or veins, and the hind {4} wings eight, but in some genera a rib, or perhaps two, may be absent from the fore or the hind wings; or an extra rib, sometimes two, may be found on the hind wings.

These modifications, and others, of the general plan of neuration have been employed as a basis upon which to found genera, or to group them together in cla.s.sification.

[Ill.u.s.tration: FIG. 4.

THE JUGUM, OR YOKE.]

Fig. 3 shows the arrangement by which the upper and lower wings of a moth are united in flight. The bristle (_frenulum_) arising from the base of the hind wing is held in place by the catch (_retinaculum_) on the costal nervure of the fore wing. It will be noticed that the bristle of the male is longer and firmer than that of the female. The latter, moreover, is usually made up of two or more strands; the catch, too, in the female is on the median instead of the costal nervure. These structures are found on the under side of the wings of most moths, but they are absent in all b.u.t.terflies. The Emperor, Kentish Glory, and Eggars may be mentioned as examples of moths lacking the connecting bristle, but all these have feather-like antennae, which terminate in a point. The Burnets have the antennae gradually thickened towards the tip (A. Fig. 2), and in this respect are somewhat b.u.t.terfly-like, but these moths have a frenulum.

The hind wings of the Swifts, and a few others grouped with them, have twelve veins, and these moths have a _jugum_, or yoke (see Fig. 4). This is a flap-like projection from the inner margin, near the base, of the fore wing; it may serve to connect the wings when the insect flies, but it does not seem to be capable of giving much help in that way. {5}

[Ill.u.s.tration: FIG. 5.

WINGS AND BODY OF A MOTH.

_h._ Head; _th._ Thorax; _col._ Collar; _lap._ Lappet; _ab._ Abdomen.

_b.l._ basal line; _b.s._ basal streak; _i.l._ inner line; _c.s._ claviform stigma; _o.s._ orbicular stigma; _c._ central shade; _r.s._ reniform stigma; _o.l._ outer line; _a.p._ apical patch; _s.m._ submarginal line.]

[Ill.u.s.tration: FIG. 6.

PALE TUSSOCK-MOTH AT REST.]

In describing a moth various markings, etc., have to be referred to, and as it may a.s.sist the reader more easily to locate the usual position of such characters the accompanying diagram has been prepared. The lines crossing the fore wings from the front edge, or margin (_costa_), to the inner edge, or margin (_dorsum_), are generally styled transverse lines; the short one is the basal; the first long one is the inner, or antemedial; the second is the outer, or postmedial; and the third is the submarginal, or subterminal.

The whole wing, less the margins, is sometimes called the disc; but it is more convenient to divide the fore wing into three parts, naming that between the base of the wing and the first line the basal area; the s.p.a.ce between the first and second lines the central or median area, and the part beyond the second line the outer area. The more or less round or oval rings or dashes on {6} the central area are the stigmata, and these characters occur more especially in the Noctuidae. The hind wings usually have a fine short line, crescent, or spot, at the end of the cell, as in the b.u.t.terflies, and there is generally a line or band beyond.

Immediately behind the head and covering the front part of the thorax is a tippet-like arrangement of scales; this is the collar. On each side of the thorax there is a shoulder lappet (_patagium_) which has its base on the front part of the thorax also. Both tippet and lappet are often peculiarly ornamented, and the former is sometimes strikingly coloured. The thorax is sometimes crested, and more frequently the body is furnished with tufts of erect hair scales.

The number of moths occurring in the British Islands is well over two thousand. The majority of these hardly ever find favour with the collector.

This is probably owing in a large measure to the fact that they belong to a division of the moth tribe which has been dubbed Micro-lepidoptera. It happens, however, that quite a number of the species included in that division are actually larger than many kinds that were placed in the other contingent styled Macro-lepidoptera. According to the most recent authorities the division of moths into two such main groups as those adverted to is entirely fict.i.tious and misleading. Possibly, when this new order of things is more generally understood the so-called "Micros" will receive their proper share of attention.

In the older systems of cla.s.sification the Clear wings (Sesiidae) were a.s.sociated with the Hawk-moths (Sphingidae), but the former family is now considered to be more closely connected with the Tineidae. The Goat-moth (_Cossus ligniperda_) has been removed from among the Bombyces, its name changed to _Trypa.n.u.s cossus_, and placed in the family Trypanidae, which is relegated to the neighbourhood of the Tortricidae. The Burnets (Zygaenidae), together with _Heterogenea limacodes_ and _H. asella_ (Cochliopodidae), also _Macrogaster castaneae_ and _Zeuzera pyrina_ (Cossidae {7} part) are removed by Meyrick to the Psychina, a group placed between that author's Pyralidina and Tortricina. The Swifts (Hepialidae) are grouped with Micropterygidae, which are considered to be primitive forms of Lepidoptera originating in the Caddis-flies or Trichoptera--a division of the Order Neuroptera.