Lappet Moth 3 – Gastropacha Species

Lappet moths are a very interesting group of moths. As we saw in the first part of this 3 part series called Lappet Moth – Trabala Species. We also noticed in the second part Trabala in Trouble. Now let us see the adult version of a species from this group. This fascinating moth resemble a dried leaf when at rest. This moth belongs to Gastropacha species of Lappet moth (Lasiocampidae) family. I found this at night under Mangalore tile roof my house staying motionless like a dry leaf. When I picked it up to get closer look it excreted a smelly liquid from its caudal end probably to startle me. It remained motionless despite all the disturbances like a dry leaf. they have a snout which resembles the stalk of the dry leaf, combed antenna is fold back on the body.

Predators of this moth are the bats, and they do not see these moth like we do. They see them through sound waves by echo location. In fact the scales of this moth is so modified that ultrasonic signals used by bats to locate these moth just fails as the scale in this moth absorb those signals. The wing scale cover reduces the potential of the ultrasonic signal reflected from these moths of Gastropacha species. Absorption of a considerable part of the reflected signal decreases the sound pressure. This property of the wing scale cover enables the moth to prevents bat from finding the moth in the night. It is invisible to us as well as bats by this great camouflage.

Camouflage, whereby animals seek to look inanimate or inedible to avoid detection by predators and prey. There are many examples of rainforest species which are cryptically colored to match their surroundings. For example, the Uroplatus geckos of Madagascar are incredible masters of disguise and are practically unnoticeable to the passer-by. An even more amazing group is the katydids, a group of grasshopper-like insects found worldwide. 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. Katydids have evolved to the point where their body coloring and shape matches leaves?including half-eaten leaves, dying leaves, and leaves with bird droppings?sticks, twigs, and tree bark. Other well-known camouflage artists include beetles, mantids, caterpillars, moths, snakes, lizards, and frogs.

Some species appear to have conspicuous coloration when they are not in the proper surroundings. For example, among the brilliant butterflies of the forest, the magnificent electric blue Morpho, has iridescent blue upper wings and a seven-inch wingspan. However, because the underwings are dark, when the Morpho flies through the flickering light of the forest or even out in broad daylight, it seems to disappear. Other forest species, especially mammals, have spots or stripes to help break up the animal’s outline. In the shade created by the canopy, large mammals like leopards, jaguars, ocelots, and okapi are surprisingly difficult to see with their disruptive coloration.

There is a strong evolutionary pressure for animals to blend into their environment or conceal their shape; for prey animals to avoid predators and for predators to be able to sneak up on prey. (Exceptions include: large herbivores without natural enemies; brilliantly-colored birds which rely on flight to escape predators; and venomous or poisonous animals which advertise with bright colors.) Cryptic animals include the tawny frogmouth (feather patterning resembles bark), the tuatara (hides in burrows all day; nocturnal), some jellyfish (transparent), the leafy sea dragon, and the flounder (covers itself in sediment).

The distinction between camouflage and mimicry is arbitrarily defined in that mimicry requires that the “model” be another organism, rather than the surroundings; the arbitrary nature of this distinction between the two phenomena can be seen by considering animals that resemble twigs, bark, leaves or flowers, in that they are often classified as camouflaged (a plant does constitute the “surroundings”), but sometimes classified as mimics (a plant is also an organism). Either way, the animal is considered cryptic.

Camouflage is usually most effective when an animal is still. Cryptic animals that forage during daylight may be ambush predators, taking advantage of their ability to blend into their background. Alternatively, cryptic animals may be active predators in darkness and use their crypsis while inactive. Some cryptic animals also simulate natural movement, e.g., of a leaf in the wind. This is called procryptic behaviour or habit. Other animals attach or attract natural materials to their body for concealment.