The shade of a tree gives a much-needed respite from the sweltering heat. While checking messages on the phone, you see a movement out of the corner of your eye. A partially dried leaf moving. You presume a small insect is moving under the leaf. Then the leaf starts moving up the trunk of a tree. A closer look reveals a dirt bug, covered in small grains of sand. A camouflage mechanism. The dirt bug then adjusts the dried leaf on its back to camouflage itself further.

Camouflage. The word conjures up images of tigers camouflaged amidst reeds or the fox and deer blending in with the surrounding vegetation. Camouflage also exists – abounds rather –among creatures in the urban milieu, especially among small insects.

Camouflage or cryptic colouration is a defence mechanism that helps insects merge with their surroundings. They do it to conceal their presence or identity, either to hoodwink their predators or to deceive their prey.

There are several camouflage mechanisms such as disruptive colouration where patterns break the outline of the body, like the patterns in a zebra; and mimicry or mimesis, where an organism mimics another species that is avoided by predators. A common camouflage mechanism is background matching. “The hue and pattern of organisms perfectly blend with the colour and texture of the background. The pattern plays an ecological role in helping the insects to catch a prey or to avoid being preyed upon,” said Betsy Selvakumar, an aquatic entomologist who teaches at Women’s Christian College, Chennai.

There are some like the dirt bug that do not depend on colouration but use self-decoration with the material available around them, to disguise themselves. They cover themselves almost fully, that only the antennae and the tips of their tiny feet are visible. A variation of this is the assassin bug (Acanthaspis petax) that carries dead ants to throw spiders, their predators, off their trail.

Green, white, brown – whatever the colour be, spiders, grasshoppers, moths and other city-dwelling insects find the perfect place to blend themselves in and often escape the eyes of the city-dwelling humans.