Strategies for
Survival
PAGE 2
PAGE 1 - MATE RECOGNITION
PAGE 2 - CAMOUFLAGE and
DISGUISE
PAGE 3 - APOSEMATIC
COLOURATION
PAGE 4
- MIMICRY
PAGE 5
- SEXUAL DIMORPHISM
PAGE 6 - ROOSTING BEHAVIOUR
PAGE 7 - SEASONAL DIMORPHISM
Camouflage and Disguise
cryptic
patterns, disguise and transparency to conceal butterflies from
predators
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Green Hairstreak
Callophrys rubi
at rest on green foliage. |
Butterflies use
many means to hide themselves from
predators. Sometimes, as with the
neotropical
metalmarks ( Riodinidae ), they simply hide under
leaves, out of sight. Most other species rest in more open
situations though, and conceal themselves using techniques such as
camouflage, disguise, disruptive coloration or transparency.
The boundary
between camouflage and disguise is hard to define, but
camouflage is generally considered to describe something with a
colour, pattern and texture that enables it to blend well against a
natural background or substrate. Butterflies rest on many
different substrates including foliage, soil, rocks and tree trunks
- and various species possess colours and patterns which match each
of these backgrounds.
Disguise on the other hand describes a butterfly
or moth that has a similar appearance
to another natural object, such as a leaf or flower. Moths
often have very effective disguises - some which rest on tree trunks
resemble bits of lichen, others resemble bits of broken twig. The
caterpillars of many Geometrid moths look exactly like twigs, and
even have small projecting false "thorns".
Camouflage
Amongst British
butterflies the Orange tip
Anthocharis cardamines
is a good example, difficult to spot when at rest on the white
flowers of garlic mustard.
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Orange tip
Anthocharis cardamines,
well
camouflaged at rest on garlic mustard flowers. |
Disguise
The Brimstone
Gonepteryx rhamni,
is a superb example of disguise, being coloured and shaped like a living leaf, complete with raised
"veins".
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Brimstone Gonepteryx rhamni,
perfectly disguised as a leaf. |
In the tropics there are many
species which are disguised as dead brown leaves - examples
include the Leaf butterfly
Kallima inachus
from India, and the
Memphis
and Marpesia Leafwing butterflies of
South America.
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Zaretis itys,
a Peruvian species convincingly disguised as a dead leaf. |
Disruptive
coloration
This
term is used to describe the way in which a butterfly or moth's appearance is
visually broken up, usually by means of mottling and / or prominent
lines.
The Angle Shades moth
Phlogophora meticulosa
is a good
example - it is equally well concealed when settled amongst dead
vegetation or fallen branches.
Predators -
particularly birds, use a "search image" to locate resting moths.
They look out for a "moth shaped" object, but the disruptive pattern
of the Angle Shades breaks up it's outline and foils the bird's
search image.
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Angle Shades
moth Phlogophora meticulosa, Hampshire, England. |
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Hylephila
peruana,
a skipper from Peru. The disruptive patterning makes it very
difficult to detect amongst the dry grasslands of it's habitat in
the Andes. |
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Grayling
Hipparchia semele, perfectly disguised at rest on
dead wood |
Transparency
The colours of
butterflies and moths are produced either by pigments in the wing-scales,
or structurally, by light refracting on prism-like ridges on
the surface of the scales. Some species however are very thinly
scaled, or lack wing scales almost entirely, revealing the
transparent membrane of the wings.
Butterflies which
use transparency to conceal themselves include Ithomiine Glasswings and certain neotropical
Satyrines such as Cithaerias pireta and
Dulcedo polita.
There are representatives from other families as well, e.g. the
Chorinea
metalmarks ( Riodinidae ) of South America, and the
Lamproptera
dragontails
( Papilionidae ) of Malaysia.
Cithaerias
pireta aurora, Cocha Camunga, Rio Madre de Dios, Peru
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Vein structure of a transparent
Satyrine butterfly Haetera piera
( photo courtesy Tony
Hoare ) |
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