The moths belonging to this family are popularly known in Britain as
Burnets and Foresters. Of the former seven kinds occur in the British
Isles, and of the latter there are only three species.
All the species live in colonies, so that when a specimen is seen or
captured others may be expected to occur on, or somewhere around, the same
spot. The caterpillars bear a close resemblance to each other, and are not
always easily distinguished.
Over thirty species of _Zygaena_ are found in Europe, and about thirty-six
more have been described from other parts of the Palaearctic Region. There
are at least twenty-five Palaearctic species referred to the genus Ino, and
about ten of these are European.
By most authors _filipendulae_ is regarded as the type of the genus
_Zygaena_, Fabricius; but others refer this species, and its allies, to the
genus _Anthrocera_, Scopoli, using the Fabrician genus for _phegea_,
Linnaeus. The latter species and its allies are perhaps more frequently
referred to _Syntomis_, Ochsenheimer, the typical genus of the family
Syntomidae, the systematic position of which is near the Arctiidae. It may
be added that _S. phegea_, and also _Naclia ancilla_, have been reported as
British. There does not seem, however, to be any reason to suppose that the
occurrence of either species in Britain could be other than accidental.
{334}
THE TRANSPARENT BURNET (_Zygaena purpuralis_).
Two Welsh specimens are depicted on Plate 146, Figs. 1 and 2; these are of
the typical form. A rare aberration has the spots and the hind wings more
or less suffused with blackish (ab. _obscura_, Tutt), but a still rarer
variety has the crimson of spots and hind wings replaced by yellow (ab.
_lutescens_, Tutt).
Newman in 1861 referred an Irish specimen to _achilleae_, but a little
later, after seeing other examples, in the same year he changed the name to
_nubiginea_. Birchall (_Ent. Mo. Mag._, iii. pt. i.) figured four forms of
the species from Ireland; his _minos_ (Figs. 5a and 5b) seems to represent
two modifications of ab. _interrupta_, Staudinger, in which form the red
blotches are widely separated or interrupted by the ground colour; and his
_nubigena_ is made up of more or less typical _purpuralis_ (Fig. 6a), and a
variety (Fig. 6b), with red marks between the lower and central blotches.
The caterpillar (Plate 145, Fig. 1) is dark green inclining to olive above
and paler below; the spots are black (outer row) and yellow (inner row);
the line along the back is obscure whitish; hairs, whitish. It feeds on
thyme and burnet saxifrage (_Pimpinella_). _Trifolium_ and _Lotus_ have
also been given among other food plants. In late summer, and after
hibernation, in the spring. The moth flies in June, and is locally common
in Ireland (Clare and Galway), Wales (Abersoch), and Scotland (Oban, Loch
Etive). It has been reported from Tintagel, Cornwall, and possibly, as
suggested by Tutt, these Cornish specimens may turn out to be _Z.
achilleae_, the latest addition to our small band of Burnets. Perhaps the
Scottish specimens recorded as _purpuralis_, or at least some of them, may
prove to be _achilleae_.
This species was figured by Brunnich, in 1763, as _purpuralis_, and
authorities are now agreed that this name must be adopted in place of
_pilosellae_, Esper (1781), or _minos_, Fuessly (1782). {335}
SCOTCH OR MOUNTAIN BURNET (_Zygaena exulans_).
This semi-transparent and rather greyish moth has five reddish spots on the
fore wings. (Plate 146, Fig. 3.) So far as concerns the British Isles it is
only known to occur in Aberdeenshire, where it was discovered on the
mountains at Braemar in July, 1871, and where it may be still found by
those who are acquainted with the situation of its lofty haunts. The late
Dr. Buchanan White named the Scottish form _subochracea_, but others
consider that it is not readily separable from _vanadis_, Dalman, which in
turn is said by Tutt to be pretty much the same form of the species as that
described as the type _exulans_, Hochenwarth.
The caterpillar is dark green above, and paler below; two velvety black
stripes on the back, each stripe interrupted by yellow spots; warts with
black hairs; head, black. It feeds on _Silene acaulis_, cyphel (_Arenaria
cherleria = Cherleria sedoides_), clover, trefoils, _Azalea procumbens_,
etc.; has been known to eat dock and knot-grass: August to June. The cocoon
has been found on a stem of crowberry (_Empetrum_), and on heath and grass
stems. The moth is out in July, and, like the rest of its kindred, delights
in the sunshine.
_Zygaena achilleae_.
A specimen of this species, quite recently introduced as British, has been
kindly lent by Mr. B. Adkin. It was taken, with others, in the vicinity of
Oban, Argyllshire. Mr. Sheldon informs me that he believes that a worn
Zygaenid he captured in 1898, in the Glencoe district, was this species.
On Plate 1, with the Scottish example (Fig. 2) referred to, is also shown a
specimen from the continent (Fig. 3), and it will be noted that the former
is very like the latter. In some {336} respects this species is not unlike
some confluent-spot forms of _filipendulae_, but it is a more
slender-looking insect, and the body is more hairy. Further, the upper
basal spot of the fore wings is lengthened almost to the upper spot of the
middle pair, and the fifth and sixth spots together form an almost oval
mark. Both specimens depicted seem to be referable to var. _viciae_,
Hubner. In the typical forms the spots are larger. A yellow form ab.
_flava_, Oberthur, is known on the continent.
The caterpillar, after Hofmann, is figured on Plate 1, Fig. 5. It is said
to feed on _Astragalus_ and _Coronilla_.
NEW FOREST BURNET (_Zygaena meliloti_).
Two examples of this, normally, five-spotted little species are shown on
Plate 146, Figs. 4 [male], 5 [female]; a variety, referable to ab.
_confusa_, Staudinger (spots run together forming streaks somewhat as in
_purpuralis_), is depicted in Plate 148, Fig. 1. Occasionally a sixth spot
is in evidence (ab. _sexpunctata_, Tutt). A form in which the body has a
red belt is known abroad as ab. _stentzii_, Freyer, and examples having
traces of this belt have been recorded from the New Forest, which, it may
be added, is the only locality in Britain producing this species.
The caterpillar is of a dull pale greenish colour, with numerous black
speckles; three whitish lines on the back, the central one greenish tinged
and broader than the others, which are interrupted on each ring by a yellow
spot; between the lines is a series of black dots, one on the outer edge of
each ring; hairs, from greenish warts, white and short; head, black, dotted
with white. It feeds on bird's-foot trefoil (_Lotus corniculatus_), and
other trefoils and clovers: August to May. Sometimes the caterpillars do
not complete growth until they have passed two winters in hibernation. The
cocoon, which is yellow or yellowish white, has been found on a grass stem,
but {337} it is generally placed so low down among herbage that it seems to
be rarely detected.
The moth is out in June and early July.
As previously stated the only part of Britain that the species inhabits is
the New Forest, Hampshire. Here it was first met with in Stubby Copse,
about 1869, but was apparently not distinguished from _Z. trifolii_ until
1872. It is now less frequent in its old haunt than formerly, although it
still occurs there; in other spots around, I believe, it is not uncommon in
some years.
Some authorities refer this species to _viciae_, Schranck.
FIVE-SPOT BURNET (_Zygaena trifolii_).
Four specimens of this species are portrayed on Plate 146. In the typical
form (Figs. 7 [male], 8 [female]) the central pair of crimson spots are
united and often form a large blotch; ab. _orobi_, Hubner (Figs. 6 [male],
9 [female]), has the spots placed well apart. Other more or less frequent
aberrations are depicted by Mr. Horace Knight on Plate 148 where Fig. 2
represents ab. _glycirrhizae_, Hubner (spots 3, 4, and 5 united); Fig. 3,
ab. _basalis_, Selys (spots 3 and 4 united with the basal pair); and Fig.
4, ab. _minoides_, Selys (all the spots united, forming an irregular
patch). An extreme development of the last-mentioned form has been named
ab. _extrema_, Tutt (see _Entom._ xxix., p. 341, Fig. 2). Specimens with a
sixth spot as in _Z. filipendulae_ have been occasionally recorded, and an
example with the lower spot of the central pair absent has been taken in
West Sussex by Mr. W. M. Christy, who has also obtained a number of
specimens of a yellow form (ab. _lutescens_, Cockerell) in the same
locality. The yellow form is shown on Plate 148, Fig. 5. Some of the yellow
aberrations also exhibit variation in the spots pretty much as in the
ordinary form. In some localities, especially marshy ones, the spots on
{338} the fore wings and the hind wings are occasionally dull orange; and I
have noted specimens in the Weybridge district, Surrey, with the spots on
the fore wings of a pinky ochreous colour, whilst the hind wings were of
the usual crimson. Such "aberrations" as those last mentioned probably
result from weather exposure. In 1899, Mr. G. B. Corbin recorded the
capture, near Ringwood, Hants, of a specimen which had the spots on the
fore wings and the red of the hind wings darkened over with dull smoky
black, so that the insect when seen at a distance seemed to be wholly
black. Dr. Hodgson has recently obtained several of these melanic specimens
in Sussex. A form with the spots and hind wings suffused with brownish has
been named ab. _obscura_, Oberthur.
With regard to six-spot examples referred to this species, I am inclined to
suppose that they may be the offspring of a chance pairing of _trifolii_
and _filipendulae_. That such crossing does occur in nature I have
evidence, as on one occasion I found four mixed pairs, the male being
_trifolii_ in each case, and the female typical _filipendulae_. This was in
the Weybridge district, where I had come across a colony of the latter
species and was closely examining the specimens for aberrations.
The caterpillar (Plate 145, Fig. 3) is green inclining to yellowish and to
bluish, with black marks on the back; a series of black streaks low down
along the sides. It feeds on _Lotus corniculatus_, and on other trefoils
and clover: July to May. Sometimes taking two years to complete its
changes.
In damp meadows the moth is out in May and June, but in marshes it does not
appear, as a rule, until July, and may be found in early August. The marsh
specimens, which are sometimes rather large in size, have been referred to
_palustris_, Oberthur, and are treated by Tutt (_Nat. Hist. Brit. Lep._,
vol. i.) as a sub-species.
[Illustration]
2 Pl. 146.
1, 2. TRANSPARENT BURNET.
3. SCOTCH BURNET.
4, 5. NEW FOREST BURNET.
6-9. FIVE-SPOT BURNET.
[Illustration]
2 Pl. 147.
1, 2. NARROW-BORDERED FIVE-SPOT BURNET.
3-5. SIX-SPOT BURNET.
6, 7. SCARCE FORESTER.
8, 9. THE FORESTER.
10, 11. CISTUS FORESTER.
{339} In the British Isles, the species is apparently confined to England
and North Wales. In the former country it is locally common in most of the
southern counties; still more local in the eastern counties, and northwards
to Lancashire and Yorkshire. There are records from Armagh and Fermanagh,
but Kane appears to doubt the occurrence of the species in Ireland. There
is no doubt that the next species has frequently been mistaken for the
present one, therefore the actual range of _trifolii_ in the British Isles
has probably not been fully ascertained.
NARROW-BORDERED FIVE-SPOT BURNET (_Zygaena lonicerae_).
As will be seen from the two specimens represented by Figs. 1 [male] and 2
[female] on Plate 147, this species bears considerable resemblance to ab.
_orobi_ of _Z. trifolii_. The chief differences are in the rather longer
fore wings and the more pointed tips of the hind pair; the borders of the
hind wings are often narrower. In a broad way, it may be stated that the
general tone of colour in the male of _lonicerae_ is bluer than that of
_trifolii_. The union of any two or more spots is rarely seen in this
species in Britain, but specimens with all the spots joined together have
certainly been noted. A yellow form, ab. _citrina_, Speyer (= _flava_,
Oberthur), is known on the continent, and Barrett states that it has
occurred in England. In ab. _lutescens_, Hewett, the hind wings are orange.
Ab. _eboraceae_, Prest, is semi-transparent, steel blue; the spots and the
hind wings are pink, the border of the hind wings brown, and the fringes of
all the wings are whitish.
The caterpillar (Plate 145, Fig. 2) is very similar to that of the last
species, but the black marks on the sides are heavier, and the hairs of the
body are longer. It feeds on trefoils and clover, and sometimes passes two
winters before becoming full grown. The cocoon, which is attached to stems
of grass, etc., is generally placed well up above the ground, so that it is
readily seen. {340}
The moth, which is out in late June and in July, occurs in woods and
plantations; also said to be found in meadows, and on rough waste ground,
as well as in marshes and salterns. The distribution is much as in the last
species, but it is plentiful in East Yorkshire, and the range extends to
Cumberland and Northumberland.
SIX-SPOT BURNET (_Zygaena filipendulae_).
This species (Plate 147, Figs. 3-5) is the most generally common of our
Burnets. Perhaps the most frequent form of variation in the spots of the
fore wings is that in which the outer pair run together, and so form a
blotch; but union of the middle pair is not an uncommon occurrence. In ab.
_cytisi_, Hubner, the three pairs of spots are each united, so that the
fore wings have three separate blotches, and when these are of a dull
scarlet instead of the usual crimson, ab. _ramburi_, Lederer, is
represented. Occasionally, all the spots are united, as in ab. _cytisi_,
and the blotches thus formed are connected by reddish streaks in various
modifications leading up to ab. _conjuncta_, Tutt, which has all the spots
merged into a large blotch, extending over the disc of the fore wings. From
the normal crimson, the spots and the hind wings vary now and then to
orange (_aurantia_, Tutt), or to yellow (ab. _flava_, Robson = _cerinus_,
Robson and Gardner); intermediate shades between these two extremes, and
the typical coloration, are rather more frequent. I am indebted to Mr. R.
Adkin for the loan of the example of the yellow form shown on Plate 148,
Fig. 6. Pink, and orange, forms have been noted from various parts of
England, but they seem to occur, or have been found, more especially in
Cambridge and the north-east corner of Essex. Fig. 7, Plate 148, represents
an example of ab. _chrysanthemi_, Hubner, and is copied from Oberthur's
_Etudes d'Entom._, xx., Plate 8, Fig. 134. A few specimens referable to
this form, probably not exceeding half a dozen altogether, have been
recorded as taken in England. In typical _filipendulae_ the dark blue
border of the hind wings is narrow, but in ab. _hippocrepidis_, Stephens
(_tutti_, Rebel), the borders are rather broad. Another character of this
form is that the nervule upon which the sixth spot is placed is here of the
ground colour, and therefore divides the spot. (Plate 147, Fig. 3.) At
Northwood, Middlesex, I have found this form in May and June, and also in
the Weybridge district, Surrey, in late July; and, it may be added, there
was a flourishing colony of _Z. trifolii_ hard by in each locality. For
this reason, plus the fact that _trifolii_ [male] is known to pair with
_filipendulae_ [female], I hold the opinion that _hippocrepidis_ is a
hybrid. It may be noted here that hybrids have been raised from the
crossing of _filipendulae_ and _lonicerae_; the sexes of _lonicerae_ and
_trifolii_ pair somewhat readily, and the hybrid offspring of such pairings
are fertile.
[Illustration]
2 Pl. 148.
1. NEW FOREST BURNET, AB. _CONFUSA_.
2, 3, 4, 5. FIVE-SPOT BURNET, VARS.
6, 7. SIX-SPOT BURNET, VARS.
[Illustration]
2 Pl. 149.
1. FESTOON MOTH: _caterpillars and cocoons_.
2. TRIANGLE MOTH: _caterpillars_.
{341} It seems, then, that _trifolii_, _lonicerae_, and _filipendulae_ have
not, so far, lost the power of fertile cross-pairing. Wherever colonies of
two of the kind exist within visiting distance of each other, there, it
appears, we may reasonably expect to find hybrids.
From a number of cocoons collected in a Yorkshire locality for _lonicerae_,
I reared, in 1907, a good many examples of that species, and also about a
dozen six-spot specimens, which agree in colour with _filipendulae_, but
they have the vein-interrupted sixth spot and broad border to hind wings,
as in _hippocrepidis_.
The caterpillar (Plate 145, Fig. 4) is greenish, with black markings and
some yellow spots, the latter chiefly on the hind edges of the rings. It
feeds in the autumn and after hibernation, on trefoils, clover, bird's-foot
(_Ornithopus_), and kidney-vetch (_Anthyllis_), completing growth in the
spring.
The moth flies on sunny days in July and August, on chalk downs, etc.,
inland, and on cliffs and sand hills on the coast, also in marshes; but, as
previously stated, it also occurs locally in meadows in May and June. {342}
SCARCE FORESTER (_Ino_ (_Rhagades_) _globulariae_).
Of the three species occurring in Britain this is slightly the larger, at
least in the male. The fore wings are green, sometimes with a slightly
golden sheen; fringes, greyish. The male is best distinguished from
_statices_ by its more slender body, and by the pectinated and rather
pointed antennae. The female is a good deal smaller than the male; the
antennae are simple, and somewhat thread-like, compared with those of the
females of _statices_ and _geryon_. (Plate 147, Figs. 6 [male], 7
[female].)
The caterpillar is green, with the raised spots inclining to bluish; two
yellowish-white lines along the back, and a dark green stripe along the
sides; head and plate on first ring of the body, black. It lives on
knapweeds (_Centaurea nigra_ and _C. scabiosa_), feeding on the leaves much
in the same manner as the caterpillar of the next two species.
The moth is out in June and July; it is partial to blossoms of salad burnet
(_Poterium sanguisorba_), and only flies in the sunshine. The late Mr. J.
Jenner Weir, who found the species commonly on the downs near Lewes,
Sussex, was the first entomologist to record it as British. The best known
localities in Sussex are Hollingbury Vale and Cliffe Hill, but it also
occurs at the Devil's Dyke near Brighton. In Kent it is found on the downs
behind Folkestone and Shorncliffe Camp.
THE FORESTER (_Ino_ (_Adscita_) _statices_).
In its most frequent form in Britain, this species is bronzy green (ab.
_viridis_, Tutt); the typical bluish green type is much less frequent. The
female is smaller than the male, but the difference in size is hardly ever
so marked as in the sexes of _globulariae_. The antennae of the male are
pectinated, but the tips are thickened. (Plate 147, Figs. 8 [male], 9
[female].) {343}
The caterpillar (Plate 145, Fig. 5) is whitish, inclining to green, yellow,
or pinkish, on the back, and the sides are pinkish brown; the hairy warts
are brown or pinkish brown, and the small head is glossy black. It feeds on
sorrel (_Rumex acetosa_), and it attains full growth, after hibernation,
about the end of April. On leaving the egg-shell in the summer, the young
caterpillar bores into a leaf, and eats the tissue between the upper and
lower skins; later on it attacks the foliage from the underside, but leaves
the upper skin intact; or the process may be reversed, and the under skin
left.
The moth is on the wing in June, sometimes late May. It occurs, locally, in
meadows, frequently damp ones, where there is plenty of ragged-robin
(_Lychnis flos-cuculi_), the blossoms of which plant it seems to prefer to
all others.
Widely distributed over England, but in Wales only recorded from Capel
Curig and Barmouth, in the north of that country (1900). In Scotland its
range extends to Moray; and in Ireland it is found in counties Wicklow,
Cork, Clare, Westmeath, Monaghan, Sligo, and Galway.
CISTUS FORESTER (_Ino_ (_Adscita_) _geryon_).
This species is much smaller than the last; the fore wings, the outer
margins of which are somewhat rounded, are bronze green, but, in the male,
rather dull in tint, sometimes tinged with golden towards the base. The
antennae are more stumpy than those of _statices_, but in other respects
they are similar in appearance. The female is not much smaller than the
male. (Plate 147, Figs. 10 [male], 11 [female].)
The caterpillar is yellowish white, with bristle-bearing warts of pretty
much the same colour; three lines on the back, the central one whitish,
edged on each side with purplish, the others waved and of a claret colour;
a reddish-brown stripe low down {344} along the sides; head and plate on
first ring of the body black, the latter edged in front with yellowish. It
feeds on rock rose (_Helianthemum chamaecistus_). At first it attacks the
leaf from the upper side, and partly burrows therein; when older it clears
away patches from the under surface, leaving the upper skin of the leaf
more or less transparent; as it approaches full growth it likes to take its
meals in the sunshine, and then eats the top skin as well as other parts of
the leaf, and also tender shoots: July to May. The moth is out in June and
July, as a rule, but is sometimes observed in May. Its haunts are on warm
slopes of chalk downs and limestone hills, where it flies in the sunshine.
This species was first noted as British in March, 1860, when specimens from
Worcestershire were recorded as _Procris tenuicornis_. It seems, however,
to have been considered doubtfully distinct from _statices_ until 1863,
when the caterpillar was found, and the occurrence of the species in
several other English counties recorded. At the present time _I. geryon_ is
known to inhabit Sussex (Brighton and Lewes districts), Kent (Canterbury
and Shorncliffe), Bucks (Aylesbury and Tring), Oxfordshire (Chinor),
Gloucestershire (Cotswolds), Worcestershire (Malvern Hills), Derbyshire and
North Staffordshire (Bakewell and Dovedale), Yorkshire (Richmond, Barnsley,
Sheffield, etc.), and Durham (banks on the coast). In Wales, it is
sometimes common on Great Orme's Head, Carnarvonshire.