Insect Camouflage L. Jones

Insect Mimicry and Camouflage

The insect world is perhaps one of the most diverse on the planet. When one considers the very scope of the plethora of insect species, one cannot help but be staggered by the vast variety in type, appearance, and behavior. Of course, one of the most interesting aspects of the insect world involves the ability of some species to use camouflage or mimicry in order to avoid detection or consumption by predators.

Camouflage

One of the most effective ways in which some insects can avoid becoming prey is by using camouflage. Although the exact method by which each species achieves or represents camouflage behavior, the object is always to "blend in" to their surroundings. To do this, they may either have the ability to change their color to blend in with the background, or possess a static characteristic that allows them to closely resemble a non-prey item in nature.

The Mantid is one example of an insect that uses its appearance to blend into its surroundings. Often called "praying mantis," mantids "vary greatly in shape, hue and pattern (Manning, 1997)." However, within the United States, the mantid population is limited to four types -- one native, two Oriental, and one European (Manning). Regardless of type, however, all four depend on resembling leaves or sticks in order to "trick" prey into believing they are near a plant or a twig. By the time the prey insect realizes its mistake, it is already well on its way to oblivion. Additionally, mantids also benefit from their resemblance to plants and sticks in their ability to avoid detection from animals that prey on them. Chief among these animals are birds.

Another example of an insect using camouflage is the moth. Although they do not rely as much on their camouflage ability to acquire prey as do the mantis', they possess an uncanny ability to use color as a technique to "disappear" into their surroundings, as well as an ability to use their shape to merge into the texture of whatever surface on which they alight.

Although moths in general do not actively "color change," the do have the ability, through natural selection, to slowly adapt to changes in environment over time. One of the most famous examples of this occurred in Great Britain, where formerly white moths gradually darkened in color along with the pollution-stained bark of trees during the industrial revolution. The simple fact was that the naturally white moths increasingly fell prey to birds due to their contrasting color with the darkening bark. Because the darker moths survived longer, they had more opportunity to reproduce. Hence, today the white moth is significantly more rare in that country.

Although not often considered an "insect," the inch worm also is a good example of camouflage in its ability to resemble a twig. It does this, according to Hilda Simon in her work, "Insect Masquerades," with its ability to "grasp the stem it is perched on with its hind-most prolegs," allowing it to stretch its body in the air to resemble a stem.

Mimicry

Another method by which some insects use camouflage as a survival or prey acquisition technique is by mimicry. In simple terms, insects use mimicry to resemble another organism "in color, pattern, form, behavior, or a combination of these to another organism or object (the model) (Brewer, 2000).

In order for an insect to truly mimic another organism or object, it must display three components, including its ability to "model" the species or object being mimicked, to "mimic" the look or actions of the other species or object by appearing like the model, as well as to successfully "dupe" either the predator or the prey (Brewer). Additionally, there are specific types or kinds of mimicry.

One of the most interesting types of mimicry is displayed by "aggressive mimics." These kinds of insects use mimicry to aid in its acquisition of prey. Some great examples of these organisms include female fireflies that mimic the signals of other species, and then capture and consume the attracted male fireflies of that species, flower-resembling preying mantids that capture pollinating insects as they come to feed on nectar (it is worth noting that these mantids can do great damage to crop propagation due to the destruction of pollinating insect groups)(Brewer).

Another type of mimicry is known as Mullerian mimicry. Many people consider this type of mimicry to be far more complex than the simple aggressive type. This is because these types of insects use their ability to resemble an unrelated species in order to appear distasteful to prey. This may be trough appearing "dangerous," or decidedly bad tasting, through "APO somatic...

Examples of insects that utilize Mullerian mimicry include honey bees, tree frogs, and lady beetles.
Another important fact is that there are certain species that are mimicked more than others. Of these, the Ant is particularly popular among the mimics. This is believed to be the case due to the ability of ants to sting and bite prey and predator alike. Thus, organisms mimicking ants mimic behavior by "acting fidgety and busy, mimicking the ant's behavior which allows it into the ant's nest (Rossetti, 1999)." Additionally, grasshoppers, grasshoppers, stick insects, and aphids will also mimic ants, especially in their early life-cycle stages. For example, an aphid's back end resembles an ant's head, and its movement behavior of its hind legs can allow them to resemble ant antennae. Further, a full eighty species of rove beetles can inhabit ant's nest due to their resemblance in color, shape, and chemical mimicry (Rossetti).

Finally, another type of mimicry that also tends to overlap with the other types is known as "Batesian" mimicry, in which "a harmless mimic resembles an unpalatable, dangerous, or otherwise protected model (Brewer)." Again, the insect achieves this by way of sound, appearance, or behavior. For example, a Viceroy butterfly will model a bad tasting Monarch butterfly in order to avoid being eaten (Brewer).

In order to appreciate the overlapping qualities of each "type" of mimic, consider the following table, taken from Brewer's Entomology page:

Continuity of Mimicry Types

Unpalatable or dangerous

Somewhat unpalatable or dangerous species

Palatable and harmless species

Mullerian mimics

Batesian mimics species resemble each other and a more protected species mimic a protected species

Species examples: Saudi Arabia

In order to understand the diversity and behavior of camouflage and mimic insects, it is useful to closely examine a group of these species. One of the most interesting habitats for these insects is found in Saudi Arabia, where several examples can be found. Consider the following example found in the form of a moth, related by writer Marijcke Jongbloed in her work "Disappearing Acts: nature's camouflage artists":

One of the first to attract my attention was a tiny day-flying moth that appeared to be white as it fluttered from plant to plant. I was keen to photograph it but every time it settled down it seemed to disappear in front of my eyes. Each time that I approached the place where it had apparently dissolved into thin air it magically reappeared, taking off again from its sandy or grassy perch with its conspicuous fluttering white wings...To my surprise it transpired that the moth was in fact strongly colored with red and black polka dots on a white background. Such an apparently conspicuous pattern hardly seemed to be a good basis for the magnificent camouflage had almost thwarted my photographic efforts. Surprisingly however, when this moth sits on sand it becomes well nigh invisible since the pattern of dots break up the outline of the insect, rendering it virtually impossible to distinguish until it moves. (Jongbloed, 1999)

Another example found in Arabia is the caterpillar of the species. Again, according to Jongbloed, the juvenile caterpillars used camouflage to avoid being eaten, however in this case, they used their contrasting bright white conspicuousness in order to mimic another bad tasting species, and were thus, left alone.

Examples of the mantis variety are also found in Saudi Arabia. Here, these include a colorful variety, known as the Striped Mantis, which uses its color to blend in completely with the native Euphorbia bush. Otherwise known as a Blepharopis Mandica. Additionally, a grasshopper species with "green and straw colored limbs" is known to hide amongst bushes and other vegetation. Additionally, in another variety found in the same area, its main color is beige instead of green, allowing it to hide very well in rocky areas (Jongbloed).

Interestingly, some forms of insect camouflage can at times prove to be precarious for humans. Consider, again, Jongbloed's account of an Arabian wadi, or valley:

Predators like mantises use their camouflage for two purposes: protection against predators and disguise against their own prey. This is also the case with the two large insect predators of the wadis: the giant water bug (Lethocerus niloticus) and the water scorpion (Laccotrephes fabricii). On numerous occasions I have encountered a pond within a wadi which, on first investigation, seemed to be devoid of animal life. One only had to sit down quietly however and…