Caterpillars are the larval form of the Order Lepidoptera (the insect order consisting of butterflies and moths). They are mostly herbivorous food habit, although some species are insectivorous. Caterpillars are voracious feeders and many of them are considered pests in agriculture. Many species of moths are known in their stages of Caterpillar because of damage caused to fruit and other agricultural products.
In geometrids, also known as inchvorms or Loopers, are so named because of the way they move, appearing to measure the earth (the word geometrid means earth in Greek-meter), the main reason for this unusual move is the elimination of nearly all the prolegs except the clasper terminal segment.
Caterpillars have soft bodies that can quickly grow between moults. Only the head capsule is hardened. The mandibles are hard and sharp for chewing leaves (this is in contrast to most adult Lepidoptera, which greatly reduce or soft mandibles). Behind the mandibles of caterpillars are spinnerets, for manipulating silk.
Many animals feed on caterpillars as they are rich in protein. As a result caterpillars have evolved various means of defense. The appearance of a caterpillar can often repel a predator: its markings and certain body parts can make it seem poisonous, or bigger in size and thus threatening, or non-edible. Some types of caterpillars are indeed poisonous, and are capable of shooting acid.
Many caterpillars are cryptically colored and resemble the plants that nourish and may even have parts that mimic plant parts such as thorns. Their size varies from as little as 1 mm to 75 mm (about 3.0 in). Some objects in the environment looks like bird droppings. Many animals enclosed within a silk galleries, rolled leaves or between the leaf surface mining. Caterpillar from that grow in the spring feed on oak and Catkins appear zeleni.Leto brood appear as oak grančicama. Diferencijal development is associated with the content of tannins in the diet.
Some caterpillars obtain protection by associating themselves with ants. The Lycaenid butterflies are particularly well known for this. They communicate with their ant protectors by vibrations as well as chemical means and typically provide food rewards.