heavy shading of its under surface thus
showing that mere identity of colour between
an animal and its surroundings does not in
itself afford protection, but rather the re-
verse. The other dummy is skilfully painted
with a dark tint above shading through in-
creasing paleness to white beneath, with the
result that an effect of flatness and unreality
is produced. At a distance of four feet this
dummy is practically invisible.
The principle of shadow neutralization
or obliterative colouring is now often
spoken of as " Thayer's Law." Its recog-
nition has served to indicate new avenues
for inquiry, and to add fresh zest to nature
study in the open. Many questions are
being asked with hopeful insistency which
only a few years back would have seemed
unanswerable. For instance, we want to
know and we believe that we shall dis-
cover what is the precise optical effect
upon each other of two differently coloured
areas in juxtaposition ; what is the exact sig-
nificance of certain types of pattern which
occur commonly in nature as, for example,
along the margins of butterflies' wings ;
why many insects, which are startlingly con-
spicuous close at hand, or in a room, should
become to all intents and purposes invisible
when looked at from a short distance in
their natural environment.
Already much useful and illuminating
work has been done not a little of it by
enthusiastic amateurs. One " spare-time
naturalist," Mr. Joseph Neale, of Bourne-
mouth, has paid particular attention to the
well-known puss-moth caterpillar in the
progressive stages of
its growth, and has
reared many hun-
dreds of these insects
on bushes in his
garden. In the earlier
stages of its develop-
ment, this caterpillar
feeds chiefly at night,
and rests during the
Photo: Hugh Main.
The caterpillar of the
Merveille du Jour
Moth (Agriopis aprilind]
as seen upon the bark
of the oak.
day, in full view,
upon the upper sur-
face of a leaf, where
thanks to its dark
coloration it has the
appearance of a hole
torn or nibbled in
Photo: Hugh Main.
The Moth, Boarmia
gemmaria (Rhomboidaria),
resting on a rock.
1 08
CURIOSITIES OF INSECT LIFE
the substance of the leaf. This is because this statement. Some such as the cater-
the holes in, and spaces between, leaves-^- pillars of the " pebble prominent " and the
when the foliage is seen in a strong light- " coxcomb prominent " moths look ex-
look black, or nearly so, like the young cater- actly like bits of a partially eaten leaf ; and
pillar. But if the perforation of the leaf they usually rest in contact with a portion
is more than a narrow slit, recently made,
we have to consider the somewhat curved
and highly lighted margin of the hole,
probably bordered with brown, or reddish-
brown, where the tissue t
is dead or dying. Ac-
cording to Mr. Neal,
these various appearances
are imitated with wonder-
ful fidelity by the puss-
moth caterpillar in the
intermediate stages of
its growth during the
whole time, in fact, when
it rests stretched out on
the surface of the leaf.
In the last stage of its
growth, however, before
changing to the pupa,
the full-grown caterpillar
hangs back downward
from a petiole or a leaf-
edge. It is now too big
to pose any longer as a
hole in a leaf! But,
" when attached to its
support at a high angle,
and seen laterally as a
passing bird might espy
it, it presents the appear-
ance of two green leaves
against a background of
purple bark or shade ; while in a horizontal
position which on the average of occur-
rences in the foliage of a large Populus
must be the commonest posture the
dorsal saddle is an accurate copy of the
slightly upturned tip of a fore-shortened
leaf."
In this family (Notodontidce) of the " puss"
and " prominent " moths many of the cater-
pillars are of most curious form, and
assume remarkable attitudes when at rest,
while the colouring is often very complex.
These characters, working together, serve
to disguise the insects in a most wonderful
way \vhen they are in the open, and among
their normal surroundings although, if we
see one of them for the first time in a card-
board box, we shall find it difficult to credit
of the leaf on which they have been feeding !
The resting caterpillar of the lobster moth
resembles a dried and crumpled leaf ; but
when disturbed it assumes a menacing or
Fhoto: A Harold Bastiti.
A remarkable illustration of the principle of " life-saving by
colour" is provided by the Crimson Underwing Moth as seen
on the trunk of an oak. The moth is almost .invisible !
" terrifying " attitude and looks like a
hobgoblin spider ! .
Other caterpillars (e.g. those of the
" Kentish-glory " moth) are so coloured as
to resemble the catkins of the trees whose
leaves they eat, or the flower-heads and
fruit-ears of grasses. Others, again, have
their bodies striped longitudinally with
dark and light lines in alternation an arti-
fice which renders them practically invisible
when they are among herbage where grasses
and other narrow-leaved plants predominate.
The colour scheme of the swallow-tailed
butterfly's caterpillar, when full grown, may
be regarded as an elaboration of the same
principle. Here we have bright green, barred
and spotted with black, which when seen
against a white or pale background renders
109
THE PAGEANT OF NATURE
the insect very conspicuous, but among the inconspicuousness. Those who know the
much-divided foliage of its umbelliferous caterpillars, and have seen examples or
food-plants serves as an almost perfect photographs of the transformed ships, will
disguise exactly as the colour scheme of not fail to trace the connexion,
the zebra causes this animal to " blend " Many protectively coloured caterpillars
with its normal background of sun-dried habitually adjust themselves in relation to
grasses on the African velt. It is an in- the angle of maximum light intensity a
teresting fact that caterpillars which are fact which has not yet received the atten-
coloured in these ways are not found on tion which it deserves. For instance, if
trees of the " broad-leaved " sort ; while we take a caterpillar of the poplar hawk-
some of those which feed on conifers have moth, at rest on a small branch of its
longitudinal stripes, in correspondence with food-plant, the stalk of which is inserted
the needle-like foliage of firs, spruces and
larches. In contrast with this, we have the
Photo : A. Harold Bastin.
The Orange-tip Butterfly at rest, showing what is "aimed at" by the
curious colour pattern on the underside of its wings.
into the neck of a bottle containing water,
we may place them insect, branch and
_^____^_______^_ - bottle upon a
turn-table, and
rotate them at
will without dis-
turbing the cater-
pillar's sphinx-
like repose. A
rough and ready
turn-table, suit-
able for this pur-
pose, may be
contrived from
t w o pieces o f
board and a long,
stout wire-nail.
Now, whenever
the caterpillar on
hawk-moth caterpillars, which live on broad-
leaved trees and bushes, and have on their
sides a row of light, oblique stripes which
its branch is
moved, we shall
find that it curves or bends its body,
this way or that, as need may be, so
as to bring itself into a particular rela-
are disposed to the longitudinal axis of the tionship with the window through which
body at the same angle which the lateral
veins of the. leaf of their food plant have to
its midrib. The anal spine, or " tail,"
which characterizes the larvae of this family,
the strong light reaches it. This will happen
Notes on the Illustrations on p. 111. 1. The
chrysalis of the Purple Emperor Butterfly
looks like a flat sallow leaf because of its
also heightens the leaf-like effect by suggest- shading . it is really quite a bulky object.
ing part of a leaf-stalk or petiole. But it is
necessary to emphasize again the fact that
these caterpillars do not look in the least
leaf-like apart from their food-plants. If
we wish to understand the significance and attitude'. ~4. The caterpillar of the Lobster
prove the efficacy of their colours as a dis-
qiiise, we must study them in the open, and
, . , rr f, r , presents a wonderful example or Nature s
Ji relation to the general effect of the Colouring, evidently planned to imitate a
surrounding foliage. Then we shall realize
how it was that a recognition of some of the
2. The Lappet Moth (Gastropacha quercifolid)
looks like a bunch of crumpled leaves. 3. The
larva of the "Coxcomb Prominent" Moth
(Notodonta camelind) resembles a partially eaten
leaf, beside which it rests in a characteristic
Moth (Stauropus fagi] resembles a crumpled
leaf. 5. The Buff-tip Moth (Phalera bucephala]
small bit of rotten twig,
the "Pebble Prominent"
6. The larva of
(Notodonta ziczac]
looks like a partially eaten leaf. 7. The larva
. , . . of the Emerald Moth (Geometra papilionaria)
caterpillars enabled our Admiralty, during Pesem bles a birch catkin. 8. The Marbled
the war, to camouflage merchant-ships into Minor Moth (Miana strigitus) on oak bark.
laws" which govern the coloration of rf - ^ ^-^ ^ (Geometra papiliomria)
I IO
EXAMPLES OF LIFE-SAVING BY COLOUR AND FORM.
The notes to these illustrations are on the opposite page. Nos. i and 5 are from photographs by A. Harold
Bastin, and Nos. 2, 3, 4, 6, 7 and 8 by Hugh Main.
THE PAGEAttT OF NATURE
Photo: Hugh Main.
The larvaa of the Kentish Glory Moth
(Endromis versicolor] resemble the green catkins
of the Birch.
again and again, immediately after the table
has been turned, for the caterpillar seems
never to tire of adjusting itself. Can we
doubt that this remarkable light-responding
habit has become fixed, as an " instinct "
in the course of the insect's evolution,
because the colour scheme upon which its
safety largely depends " looks best " i.e.
most leaf-like when it is brought into a
given relationship with the " high light " ?
It is practically certain that many insects
e.g. moths whose wings simulate lichen-
encrusted bark instinctively come to rest,
when circumstances permit, upon a con-
gruous background. In what manner the
choice is guided, and what is the nature of
the nervous machinery involved, are points
which cannot be discussed here ; but most
observers agree that the average of " hits "
is far too high to be accounted for on a
theory of " happy chances."
Protectively coloured creatures, if their
disguise is to prove successful, must know
how to keep still ; for no sooner does an
apparently dead leaf, bit of stick, or tuft of
lichen begin to creep, than all hope of pro-
longing the deception ends. In this con-
nexion it is interesting to note that some
insects seem to pass periodically into a state
of trance, which continues during the normal
resting period perhaps for many consecu-
tive hours. Experiments conducted on
the Continent not long before the outbreak
of war show that some, at least, of the
Phasmidce, or " stick-insects," are always in
a cataleptic state when resting. A species
called Carausius morosus was the special sub-
ject of observation. It feeds at night, and
during the hours of daylight rests motion-
less with extended limbs among the twigs
of its food-plant, where its stick-like form
and greenish tints render it inconspicuous.
It seems certain that this insect's complete
tranquillity, which was once regarded merely
Photo : A. Harold Bastin.
A caterpillar of the Poplar Hawk- Moth seen
resting in full light against a background
of the same colour-value as its own body
and that of the willow leaves. Were the
leaves more numerous, as they would
normally be, the caterpillar would be prac-
tically invisible, thanks to its coloration and
light-responding instincts,
112
N
fc 3
B
D Si
o .a
THE CHANGELING
A young Cuckoo demanding "more" from its foster-parent, a Sedge- warbler
Photograph by Captain Oliver G. Pike
CURIOSITIES OF INSECT LIFE
as the normal accompaniment of slumber,
is really due to catalepsy or to " auto-
catalepsy," as it is called, since the condition
arises from unknown inner causes, and the
insect cannot be hypnotized artificially, like
rabbits, crayfish, and some other beasts and
birds. The muscles of Carausms, during its
diurnal inactivity, are in the condition which
physiologists call flexibilitas cerea, or wax-
creatures, when lying motionless in an ex-
posed situation, are not only protected by
their own coloration, but derive benefit
from the presence of any conspicuous object
which may be near them. Indeed, there is
reason for thinking that certain animals in-
stinctively make use of this " law of prox-
imity," as we may call it, by coming to rest
in a spot where they may hope to profit, for
Photo: A. Hare l<1 Bastin.
The caterpillar of the Pine Beauty Moth displays the protective value of its stripes
among the pine "needles" on which it lives.
like flexibility ; that is to say, they are
strained, but not extremely so, and if further
stretched they remain in the new position.
Moreover, the insect evinces no sign of
animation, even when mutilated. Although
these astonishing facts have only recently
come to light, and have so far been demon-
strated in but few instances, they afford
strong presumptive evidence that many
insects pass periodically into a state of
self-induced trance, more or less complete.
The whole question calls for investigation,
and new facts are likely to be disclosed at
no distant date.
Naturalists have remarked that some
example, by the strong light reflected from
a white stone or from the surface of water.
In such places the strong white reflection
tends, by its very brilliance, to conceal all
relatively sombre objects in the immediate
vicinity. The eye is dazzled, as we say, by
the brightness, which powerfully stimulates
the sensitive retina, and (as it were) rivets
the attention of the brain, so that neigh-
bouring objects of less luminosity are over-
looked. In view of this fact, it is interesting
to note that very many " owlet " moths
have a conspicuous pale-coloured spot or
patch in the centre of each fore-wing. In
other respects, the fore- wings which are
THE PKGEKttT OF NATURE
exposed to view when the insect assumes its
characteristic resting pose are marvels
of protective colouring ; and one might be
inclined, at first thought, to suppose that
the pale spots or patches must detract from
the concealing effect. Yet in all probability
the reverse is really the case ; for it may be
Hugh Main.
The larva of the Eyed Hawk-Moth (Smerinthus
ocellatus) shows the row of light, oblique
stripes and projection at "tail" to repre-
sent part of a leaf-stalk which characterize
caterpillars of its family.
shown by actual experiment that, by holding
the observer's attention, they prevent him
from detecting the tell-tale outline of the
insect ; so that he fails to perceive where the
real surface of the bark or stone (upon which
the moth is resting) ends and where the
imitation begins. A knowledge of these
and kindred facts gleaned in Nature's fields
led to the suggestion, made early in the war,
that a number of white objects scattered
promiscuously near the trenches in full view
of the enemy marksmen would render their
shooting no easier, if, indeed, they did not
serve seriously to deflect their aim ; while it
is possible that when (as was observed) the
Germans made use of pure white sandbags
for building the parapets of their trenches,
they were not acting freakishly, but had a
definite end in view, dictated by scientific
principles.
We see, therefore, how necessary it is that
the stereotyped habits, or ".instincts," of an
animal should closely correspond with its
coloration if the latter is to prove success-
ful as an aid to concealment. Moreover,
there must be no incongruity with physical
peculiarities such as the mode of wing-
folding when the insect comes to rest.
Thus, we find that protective colouring is
confined to those parts of the body and
wings which are exposed to view when the
insect assumes its normal sleeping or rest-
ing posture. Many of our native butterflies
including some of the gayest, have the
underside of the wings so coloured that the
resting insect is quite inconspicuous. In
the case of the " owlet " moths (Noctuidce),
which rest upon tree trunks or rocks, the
hind-wings are often conspicuously even
brightly coloured, but they are completely
hidden by the fore- wings, which are folded
roof-wise above them when the insect
settles. On the other hand, the " carpet "
moths (Geometridee), which rest with the
wings spread open, have the whole upper
wing area protectively coloured. Other
striking examples are the buff-tip moth
like a small piece of dry and decaying twig,
with its broken ends, all complete, and the
lappet-moth like a few withered and
crumpled leaves. The orange-tip butterfly,
when resting, resembles a cluster of tiny
white flowers (such as those of the cow
parsley) as they appear when seen against
a luminous green background ; while the
little green-hairstreak butterfly seems to
become a part of the bramble spray upon
which it pitches, because the underside of
its folded wings are leaf-green just the
right shade, too, to harmonize exactly with
its environment.
These are a few striking examples of
Nature's achievements as a camouflage
artist ; but in what has been written we
have merely touched, as it were, the fringe
of a vast topic, to which the novice may
direct his attention, in the confident expecta-
tion of making fresh discoveries.
1 14
The beginning of the first transformation of the Peacock Butterfly, i.e. from the cater-
pillar to the chrysalis state :
1. Six hours before the change began. 2. Thirty seconds after the change began.
3.-TRANSFORMATIONS OF A
BUTTERFLY
By T. M. BLAGKMAN
"With photographs by the Author
THOUGH it is a matter of common
knowledge that a butterfly before
attaining the winged state has to
pass a great part of its life as a caterpillar,
comparatively few people have ever thought
it worth while to watch for themselves the
successive changes right through from the
time the caterpillar ceased feeding until
the emergence of the butterfly. Yet this
transformation, which goes on daily all
around us through the spring and summer
of each year, is one of the most interesting
of the many wonderful processes of nature.
In the case of some groups of butterflies,
the caterpillar, before changing to a chrys-
alis, hangs head downwards, bound to its
support by a silken girth around its body
as well as by the " tail." In other cases
the change takes place upon or below the
surface of the ground, or sometimes, as
in the case of the " skippers," in a silken
cocoon between leaves or grasses, similar
to that formed by many caterpillars of
moths.
For the purpose of photographing the
transformations, a butterfly has been
chosen belonging to the family Nympha-
lince, which includes such familiar insects
as the fritillaries, tortoiseshells, and red
admiral. In this family and that of the
Satyrince or " browns " the caterpillar
chooses some firm object, a leaf or stem
of some convenient plant growing near,
and spinning on to it a pad of silk, hangs
head downwards during the chrysalis stage.
While casting off the caterpillar skin,
from the head upwards, the insect has to
withdraw the extremity of its body and
engage a group of minute hooks into the
threads of the silken pad before completely
*
3. One minute later.
I
5. Forty-five seconds later
6. Fifteen seconds later. 7. Fifteen seconds l^ter ? ' 8. Forty seconds later.
9. The chrysalis case 10. Twenty seconds after
bursting. change began.
11. Seventy-five seconds
later.
12. Seventy-five seconds later. 13. One minute later. 14. Two minutes later.
The second transformation, i.e. from the chrysalis state to the perfect butterfly.
THE PAGEANT OF NATURE
15. Three minutes later.
divesting itself of the skin. Fig. 5
of the series of photographs shows the
insect arrived at this critical stage. The
under surface of the last three or four
sections of its body are still attached to
the inner surface of the skin when the
terminal section is withdrawn. Then, by
means of what is evidently a most strenuous
effort, the " tail " is thrust upwards, the
insect writhing and exerting all its energy,
until eventually, if it is successful in over-
coming this difficult and dangerous period
of its existence, the hooks are safely engaged
among the threads of the silken pad.
Fig. 6 shows the insect endeavouring to
attain this end. The moment its object
is achieved and the insect knows that it
is attached to a firm support, by means of
violent shaking and twisting the caterpillar
skin is cast off and falls away. The same
movement attaches the hooks the more
firmly in the silk and ensures the safety
of the insect. Immediately after casting the
skin the chrysalis is of a light green colour,
and until the new skin becomes hardened is
very susceptible to injury.
The time passed in the chrysalis state
varies in different species, and is also
influenced by climatic conditions. Whereas
in temperate climates some species always
pass the winter in the egg state, others
continue as a caterpillar, and others again
as a chrysalis, there are a few which
pass the winter as a butterfly ; becoming
torpid after hiding away in some sheltered
position. A barn or haystack or hollow
tree is often chosen for this winter sleep,
and the eggs are laid after coming out
again in the spring. Such species, of
which the peacock butterfly is one, usually
pass only a short time, perhaps only ten
or fourteen days, in the chrysalis state,
during the summer.
The emergence of the butterfly generally
takes place in the early part of the day,
and the second series of photographs shows
the process so well that no description
is necessary. The wings are limp when
newly developed, so the insect rests with
them hanging downwards for two or three
hours, after which they become dry
and serviceable, and our butterfly, which
was once a crawling grub, has now become
a thing of beauty and graceful motion.
16. Two or three hours after the change began
the perfect insect is on the wing.
118
Wonders of Bird Life
Photo: y. T. A~e-m.i\
Swallows when assembling for the autumn migration frequently congregate on the
telegraph wires just before the impulse for movement quickens.
4.-THE SWALLOW AS A MIGRANT
By A. LANDSBOROUGH THOMSON, O.B.E.. D.Sc.
IT is here proposed to take the swallow
as a typical example of a migratory
bird, the subject of bird-migration,
more especially in its British aspects, having
been already discussed on more general
lines in a previous chapter. The swallow
is indeed for most people in this country
the proverbial migrant, and scientifically it
serves as a useful type. It presents a
relatively simple case, that of a summer
visitor and bird of passage which is altogether
absent in winter from these latitudes, as
compared with such common migratory
species as the song-thrush and the starling
which are represented in the British Isles
throughout the year.
The complete absence of the swallow in
winter makes the fact of its migration
obvious to all, unless the alternative of
" hibernation " be taken into account. The
view that swallows and other birds hiber-
nated, and even hibernated in the mud at
the bottom of ponds, was indeed credited
by many good naturalists in the not very
distant past ; even Gilbert White of Sel-
borne was not free from the delusion,
and the famous anatomist, John Hunter,
thought it worth while to seek evidence
against the belief by the experiment of
confining swallows in autumn in a conser-
vatory provided with tubs of water and mud.
Even at this day the idea dies hard in the
countryside, and every now and then some
fact, such as the finding of a dying bird in
a hole or the appearance of an exceptionally
early or late bird in a spell of mild weather,
is cited by the credulous as evidence in its
favour. Scientifically speaking, the hiber-
nation view has long since been exploded,
however, and so much is now known of the
actual migration of the swallow that there
remains no excuse for invoking a highly
improbable theory as an alternative ex-
planation of its winter absence.
Although much is now known of the
swallow's movements, it remains true that