How praying mantis and moths use camouflage to survive

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.

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 (warning) coloration (Brewer)," sounds, or even behaviors that "warn" prey of their potential danger. 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 to wait patiently for a few minutes before the water seemed to become alive. First the fishes start to emerge from below overhanging rocks or grasses, then the backswimmers and whirligigs resume their frantic surface activities. Next a large leaf floats by - but if you try to pick it up it bites! At least, this is the case if it is the giant water bug - I have no records of biting water scorpions as yet.

Of course, no discussion of camouflage using insects can be complete without a description of a spider species. Again, in Arabia there are several examples. However, two of the best know are the sand spider, which blends in so closely with the sand that it is almost impossible to detect, as well as the Yellow Crab Spider, which lies in wait in the middle of yellow sunflowers, awaiting the much larger pollinating bees to land within their grasp.

Finally, one of the most striking examples Jungbloed encountered within her Arabian study is found in the "huge" caterpillar of the oleander hawk moth. She relates, "Even when you know what to expect the sudden appearance of enormous eyes and the split second transformation of a peacefully munching long caterpillar into a scrunched up green ball with huge staring blue eyes is startling."

Of course, one need not venture to the oases and wadis of Saudi Arabia to find good examples of insect camouflage and mimicry. According to Jerry Powell, in his book, "California Insects," the Band Winged Grasshopper has an uncanny ability to blend into surrounding rocks, and is often only detected in flight, when its contrasting hind wing color, or in its "cracking noise" (Powell, 1981).

Conclusions:

Insect camouflage and mimicry is an exciting aspect of biological study. Not only is it striking how a particular insect can adapt to resemble other objects or organisms to avoid becoming prey, or to allow for ease of "catching" prey, but it is also interesting the degree of success these organisms enjoy due to their efforts. Indeed, many would argue that it is the very success of the insect world that spawned human camouflage technology for use in warfare. However, despite all of humankind's best efforts, they have yet to achieve the skill and efficiency the insect world utilizes its camouflage abilities -- so much so that even in today's world many insect species can evade even the most trained human eye. Insect camouflage and mimicry is yet another example of the amazing diversity of the biological world.