Different pests cause different damage
Insects can become pests in the garden when they cause damage to garden plants. The signs of damage vary, typically depending on the way that the insect feeds on the plant.
Some insects have chewing mouthparts, leaving tears and holes; others have piercing-sucking mouthparts, often causing wilting, yellowing, or browning on plants.
Pest insects can also be classified by the types of damage they cause. For example, defoliators tend to feed voraciously and strip a plant nearly bare. Many caterpillars fall into this category. Other insects include leafminers, which burrow into the leaves of plants leaving tell-tale tunnels in the leaves. Then there are gall makers and wood/phloem borers. Learn more by reading "Different Pests Cause Different Damage."