Many insects of the tropical rainforest depend on camouflage to protect themselves from predators.
Some are green or brown-colored, and so blend into their surroundings.
Some species, such as the stick insects, change color slowly to adjust to changes in the background.
The glasswing butterfly of South America has transparent wings through which the background is clearly visible.
Shadows provide predators with important visual clues. They give objects depth and outlines.
Several insects have developed ways of hiding their shadows.
Lateral structures in the form of plates, hairs or outgrowths help insects such as caterpillars merge into the substratum.
Many other species are flattened and crouch close to the surface they are mimicking.
To offset the shadows produced by the vertical shafts of light in the tropical rainforest, some caterpillars are countershaded-the undersurface is a lighter shade than the upper.
When viewed from the side, the caterpillars appear flat rather than round.
An insect's outline may also be blurred through disruptive coloration, when bright patches stand out from the rest of the body, which merges into the background.
The stripes in caterpillars and grasshoppers commonly have this effect, as well as breaking up an insect's bilateral symmetry.
Some insects masquerade as commonplace items in their surroundings. Several mimic living, dead or decayed leaves.
With their greatly flattened bodies and legs, leaf insects are able to imitate a cluster of slightly chewed leaves.
Leaf mimics are often further protected by realistic markings of disease patches or bird droppings.
Treehoppers, plant-sucking bugs of the Central and South American rainforests, have pronotums that may be enlarged to produce a thornlike appearance, or may be knobbed and black, resembling ants.
Other structures that are successfully mimicked are seeds by weevils and bird droppings by caterpillars.
The behavior of the mimics frequently accentuates the deception. Many remain immobile for long periods, or freeze when danger threatens.
Leaf and stick insects gently rock back and forth to simulate movement in a breeze.
Some butterflies fly hesitantly, like falling leaves.
Species that use camouflage often have a second line of defense to use when their disguises fail.
Some drop to the ground and feign death.
Others attempt to startle a predator.
When threatened, Choerododis rhombicollis, a leaf-mimicking mantis from Central America, will turn toward its aggressor, exposing the undersurface of its large, flat pronotal shield, appearing to increase in size.
As it lunges toward the predator, it rubs its forelegs on the pronotal shield, making a scraping sound.