What insect life cycle stage is most damaging to cotton plants?

The larval stage is the most damaging to cotton plants primarily because larvae, often referred to as caterpillars, are in a developmental phase where they have high nutritional needs to support their growth. During this stage, they actively feed on the cotton leaves, bolls, and stems, which can lead to significant damage. The feeding behavior can cause defoliation, reduced photosynthetic capacity, and decreased yield as vital plant resources are consumed.

In contrast, the egg stage contributes little to immediate damage since it involves the development of the insect and requires waiting until the larvae hatch. The adult stage, while capable of feeding, does so much less compared to larvae and often serves more in reproduction than in significant plant damage. The pupal stage involves transformation and is non-feeding, thus not causing any direct harm to cotton plants at that time. Therefore, the larval stage is the most critical phase concerning immediate impacts on cotton health and productivity.