Discussion is done on various insect camouflages. History, mechanisms, importance, methods, advantages and disadvantages of camouflage in insects. The whole topic is very carefully discussed with proper photographs.
2. 1
Camouflage refers to the use of a combination of materials, illumination or colouration that
makes an insect blend in with its environment, or makes it harder to spot. Some types of
camouflage are also used to disguises insects as something else. One cannot help being
impressed by the near-perfect camouflage of a moth matching the colour and pattern of the
tree on which it rests, or of the many examples in nature of animals resembling other objects
in order to be hidden. The Nobel Prize winning ethologist Niko Tinbergen referred to such
moths as ‘bark with wings’, such was the impressiveness of their camouflage. On a basic
level, camouflage can be thought of as the property of an object that renders it difficult to
detect or recognise by virtue of its similarity to its environment (Stevens & Merilaita, 2009).
The advantage of being concealed from predators (or sometimes from prey) is easy to
understand, and camouflage has long been used as a classical example of natural selection.
Perhaps for this reason, until recently, camouflage was subject to little rigorous
experimentation – its function and value seemed obvious.
The natural world is full of amazing examples of camouflage, with the strategies employed
diverse and sometimes extraordinary. These include using markings to match the colour and
pattern of the background, as do various moths, and to break up the appearance or shape of
the body. Predators and prey alike use camouflage to avoid detection. During this
phenomenon, prey may change their skin colour or disguise themselves as per their
surrounding colour so that other predators cannot detect them.
o Katydids are nocturnal insects which use their cryptic coloration to remain unnoticed
during the day when they are inactive. They remain perfectly still, often in a position
that makes them blend in even better.
o An insect that looks like a branch, sticks, bark, leaf is using a ‘costume’ to hide from
predators.
o Insects that camouflage have a much better chance of survival as they are less likely
to be eaten if they are hard to find.
o Caterpillars are particularly at risk from predators because they cannot fly camouflage
helps many to stay well hidden.
Camouflage has been a topic of interest and research in zoology for well over a century.
According to Charles Darwin's 1859 theory of natural selection, features such as camouflage
evolved by providing individual animals with a reproductive advantage, enabling them to
leave more offspring, on average, than other members of the same species.
Introduction
History of Camouflage in Insects
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The English zoologist Edward Bagnall Poulton studied insect coloration, especially
camouflage. His experiments showed that swallow-tailed moth pupae were camouflaged to
match the backgrounds on which they were reared as larvae. Poulton's experiment was at that
time considered to be the main method of camouflage.
The artist Abbott Handerson Thayer formulated what is sometimes called Thayer's Law, the
principle of countershading. However, he overstated the case in the 1909 book ‘Conaling-
Coloration’ in the Animal Kingdom, arguing that "All patterns and colours whatsoever of all
animals that ever preyed or are preyed on are under certain normal circumstances obliterate".
Early evolution and ecology of camouflage in insects:
Taxa within diverse lineages select and transport exogenous materials for the purposes of
camouflage. This adaptive behaviour also occurs in insects, most famously in green lacewing
larvae that nestle the trash among setigerous cuticular processes, known as trash-carrying,
rendering them nearly undetectable to predators and prey, as well as forming a defensive
shield. A green lacewing larva in Early Cretaceous amber from Spain with specialized
cuticular processes forming a dorsal basket that carry a dense trash packet. The trash packet is
composed of trichomes of gleicheniacean ferns, which highlight the presence of wildfires in
this early forest ecosystem. This discovery provides direct evidence of an early acquisition of
a sophisticated behavioural suite in stasis for over 110 million years and an ancient plant–
insect interaction.
Evolution in Colour: Peppered Moths:
The most famous example of mismatched colours first came to light in the 1950s. Coal
smoke had darkened England’s trees, so that light pepper moths, once blended nicely against
bark, now stood out against the smudgy background. A dark form of peppered moths, once
rare, became common. Researchers suspected that natural selection was the reason why, and
they tested that idea by putting dark and light moth models on trees. Birds quickly attacked
the mismatched ones, as had been predicted.
To see if predators were the instrument of their disappearance, biologist Michael Majerus
launched a massive study in 2001. He died before he could publish the experiment; it only
came out last year, completed by some of his fellow scientists, in Biology Letters. Majerus
released 4864 moths, some dark and some light, and then observed how they landed on trees
and how likely they were to escape being eaten by birds. Each day, he found, dark moths
were nine percent less likely to survive.
Fig: White form of peppered moth. Fig: Black form of peppered moth.
4. 3
Camouflage, also called cryptic coloration, is a defence or tactic that organisms use to
disguise their appearance, usually to blend in with their surroundings. Organisms use
camouflage to mask their location, identity, and movement. This allows prey to avoid
predators, and for predators to sneak up on prey. There is several importance of camouflage
in insects for their survival at ease.
1. To prey at ease:
Predators camouflage themselves to blend
into its environment in order to stalk up
their prey. This is very common incidence
of camouflaging.
2. Disguise from the predators:
Animals that use disguising camouflage
can change their entire appearance. This
makes them more elite than insects that
can only change colour as they also have
the ability to change shape and texture.
3. More threatening look:
Insect disguises its self as a much larger or
powerful animal in order to survive.
4. Protection of body:
Insects camouflage to protect their body
both physically & immunologically.
5. Signalling to others:
Camouflage is also used in signalling for
warning, mate choice and rival presence.
6. Physiological balance:
Insects maintain thermoregulation, UV-
resistance, drought-resistance through
camouflage.
Importance of Camouflage in Insects
Fig: A praying mantid matches the texture and
colour of the bark of a tree.
Fig: Katydid has the ability to look identical to
its habitat even in changing seasons.
Fig: The hawk moth caterpillar takes on the shape
of a snake when trying to act more threatening
that its venerable self to scare predators.
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a) Cellular basis:
The basis of colour change has been studied for a considerable time, and the varied
mechanisms involved, primarily with regard to endocrine and cellular control. Colour change
can involve a range of mechanisms, and these can be quite different between vertebrates and
invertebrates. However, it has been studied most with regard to changes in the state and
abundance of pigment-containing chromatophore cells. These cells can respond directly to
light (a primary response) or via visual system pathways (a secondary response), with the
latter being more relevant to camouflage. Broadly, secondary responses can involve two
processes and occur over a variety of timescales. Physiological colour change occurs over
seconds, minutes and hours, and involves dispersion and aggregation of pigment within
chromatophores. Colour change can also involve morphological processes, including changes
in the number and proportion of chromatophore types and pigment content. This includes
moulting in many species (e.g. Caterpillars can occur over days, weeks and months).
b) Metabolic and physiological costs and constraints:
Colour change is often assumed to involve physiological costs and energetic expenditure. In
cephalopods, controlling large numbers of chromatophore cells rapidly and in synchrony
continuously over time probably carries a cost that impacts on the individual's energy budget.
Pigments used in morphological colour change may also be important for non-camouflage
functions, such as immune response and health, metabolic costs and other constraints
associated with changing colour and maintaining chromatophore state may be important. The
implication is that increased food consumption occurs to offset the energetic costs of
changing colour.
c) Role of visual pathways:
Most work on how visual information drives change in appearance for camouflage has been
undertaken in cephalopods. Such work has shown that cephalopods change their patterns in
response to the size, contrast and presence of visual edges and discrete objects, among other
factors. One study on grasshoppers has shown that colour change to darker or lighter forms
occurs when the substrate is comparatively light or dark, but not simply when individuals are
put into dark containers or bright light.
d) Role of diet:
While visual feedback for colour change is undoubtedly important in many species, a role of
diet also exists in some groups, and likely often interacts with vision. For example, diet is
known to influence coloration in some spiders.
Mechanisms of Camouflage in Insects
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1. Concealing Colouration or Colour Matching:
Colour matching is one of the most basic ways insects camouflage themselves. They’re able
to blend in simply by matching the colour of their surroundings. Here insects hide against a
background of the same colour in order to protect themselves from predators and also for
hunting their prey. Some insects' colours and patterns resemble a particular natural
background. This is an important component of camouflage in all environments. In each case
the animal's coloration matches the hues of its habitat.
2. Disruptive Colouration:
Many insects use more than one colour to help them blend in with their surroundings. Spots,
stripes, and asymmetrical shapes on their bodies can help break up the outline of the insects.
The dark spots or stripes found on the insect’s skin are mainly used to camouflage themselves
and to escape from their predators. Disruptive patterns use strongly contrasting, non-
repeating markings such as spots or stripes to break up the outlines of an insect.
Fig: This butterfly matches the orange flowers
it gathers nectar from.
Fig: It can be easy to miss the grasshopper since
it’s the same colour as the blades of grass nearby!
Methods of Camouflage in Insects
Fig: This butterfly matches the bark of the tree
with the uneven stripes.
Fig: This little creature will be missed easily if
not noticed carefully.
7. 6
3. Disguise or Active Camouflage:
Some animals have the ability to change their colours and patterns to help them blend in with
their surroundings. The change in their appearance or colour which gets the blend with their
surroundings by their colour, texture and shape. Some insects can quickly change their
appearance. Other insects change colours with the season. This seasonal variation helps them
blend in with the environment at different times throughout the year.
Example: This type of camouflage is mainly seen in insects like leaf butterfly, dragonfly
katydid, stick bugs or stick insect, etc.
4. Mimicry or Mimesis:
Mimesis is when an object appears to be something that it’s not. It is coloration in a harmless
animal that is similar to another animal that is dangerous, bad tasting or poisonous. Prey
insects sometimes mimic leaves, twigs, and other objects that predators wouldn’t be
interested in. Most of the insects copycat or mimic other animals to fool and escape from
their predators. The mimicry can either be in appearance or behaviour or sound or odour.
Example: Viceroy butterfly mimic monarch butterfly to safeguard them from their predators
–like birds. Birds never attack monarch butterfly as they are poisonous.
Fig: The oak leaf butterfly closely resembles a
dead leaf to disguise itself from hungry birds.
Fig: The katydid is another type of insect that
closely resembles a leaf.
Fig: The common walkingsticks are showing
the next level disguise.
Fig: This hopper disguises like the dry leaf of
the branches of a tree.
8. 7
5. Self-decoration:
Sometimes insects use what’s available in the environment around them to blend in. Insects
actively seek to hide by decorating themselves with materials such as twigs, sand, or pieces
of shell from their environment, to break up their outlines, to conceal the features of their
bodies, and to match their backgrounds.
Example: A caddisfly larva builds a decorated case and lives almost entirely inside it. The
nymph of the predatory masked bug uses its hind legs and a 'tarsal fan' to decorate its body
with sand or dust.
6. Motion Camouflage:
Most forms of camouflage are ineffective when the camouflaged animal or object moves,
because the motion is easily seen by the observing predator, prey or enemy. However, some
insects use motion camouflage. Motion camouflage is achieved by moving so as to stay on a
Fig: Masked hunter bugs camouflage themselves
by covering their bodies with grains of sand.
Fig: The cloudless sulphur might be difficult to
spot in the fall since it mimics the colour and
pattern of yellow leaves.
Fig: These caterpillars look like they’re part of
this evergreen tree.
Fig: The larvae of many caddisfly species
make hard cases out of whatever material
they find in the environment.
9. 8
straight line between the target and a fixed point in the landscape; the pursuer thus appears
not to move, but only to loom larger in the target's field of vision.
Example: Hoverflies and dragonflies use motion camouflage; the hoverflies to approach
possible mates, and the dragonflies to approach rivals when defending territories.
7. Eliminating Shadow:
Insects having flattened bodies, with the sides thinning to an edge; the animals habitually
press their bodies to the ground; and their sides are fringed with white hairs which effectively
hide and disrupt any remaining areas of shadow.
Fig: Male Syritta pipiens hoverflies use
motion camouflage to approach females.
Fig: Male Australian Emperor dragonflies
use motion camouflage to approach rivals.
Fig: A caterpillar's fringe of bristles conceals
its shadow.
10. 9
Advantages:
1. Mimicry is advantageous in that it is a reliable way to prevent predation in that an
insect will normally not try to eat an unpalatable meal. On the other hand, insects that
are not fooled might still eat the mimic and learn the difference between the mimic
and the model.
2. Another advantage of mimicry is that it allows the mimic to move about and avoid
predation without having to stay still, as is often the case in camouflage.
3. Mimicry can also be used as an aggressive rather than defensive strategy; parasitic
Phengaris arion (Large Blue butterfly) caterpillars mimic ant predators so as not to be
detected by them when they invade the ant nests and eat their larvae and eggs (Witek
et al. 2008).
4. Insects with better camouflage are more likely to survive.
5. Insects that survive will reproduce and pass their colouring on their offspring.
6. It can be used as beautification.
Disadvantages:
1. Mimicry that involves pheromones and aposematic coloration or other warning
signals can be costly to the organism (Blount et al. 2008).
2. Furthermore, if the model species goes extinct, migrates, becomes less toxic, or
evolves to look different than the mimic, then the mimic could find itself in a highly
unfavourable situation.
From the long discussion we can reach to a conclusion that camouflage is very special ability
to insects. Whether in self-protection or in preying others camouflage helps insects very
much. This feature of insects made them mysterious a well as interesting to us. It has made a
vast diversity among insect world. Through several evolutions insects have achieved really
interesting camouflages for the survival, advantageous life, physical needs etc. And they have
become the researchable beauties to us. Isn’t it?
Advantages & Disadvantages
Conclusion
11. 10
1. Evolution in Color: From Peppered Moths to Walking Sticks – National Geographic
2. Camouflage – Wikipedia
3. Benefits of insect colours: a review from social insect studies- Oluwatobi Badejo,
Oksana Skaldina, Aleksei Gilev & Jouni Sorvari
4. The Importance of Camouflage – Prezi.com
5. Stevens M, Merilaita S. 2011. Animal camouflage: from mechanisms to function.
Cambridge, UK: Cambridge University Press.
6. Camouflage – Definition, Camouflage Animals, Examples – BYJU’S
7. 32 Examples of Camouflage in Nature – Project Learning Tree
8. Exploring disguise and mimicry camouflage with youth - Michigan State University
9. Why do animals have different color patterns? - Michigan State University
10. Insect Camouflage - www.conservationindia.org
11. 11 Amazing Examples of Insect Camouflage – Treehugger
12. Balogh, A.C.V., G. Gamberale-Stille & O. Leimar. 2008. Learning and the mimicry
spectrum: from quasi-Bates to super-Muller. Animal Behaviour
13. Blount, J.D., M.P. Speed & G.D. Ruxton. 2008. Warning displays may function as
honest signals of toxicity. Proceedings of the Royal Society B
14. Cook, L. M., R. L. H. Dennis, and M. Dockery. 2004. Fitness of insularia morphs of
the peppered moth Biston betularia. Biological Journal of the Linnean Society
15. Camouflage 101 – Cryptics - University of Wisconsin-Milwaukee
16. Hiding in plain sight: How city insects have mastered the art of camouflage –
www.scroll.in
References