Integument: Structure and Function

The integument is composed of the cuticle and the underlying epidermal cells that secrete the cuticle. The cuticle serves as the exoskeleton of the insect, the site for muscle attachment, the first line of defense from fungi, bacteria, predators and parasites, and environmental chemicals, including pesticides. The integument functions in locomotion, breathing and respiration, feeding, excretion, protection from desiccation, behavior, osmoregulation, water control, and as a food reserve. The many roles played by the integumentary covering of insects are in part reflected in the complexity of its structure and chemistry, and in the special ways it is adapted to function in the ecology of its owner.

Despite many species-specific features, there are certain common features in the integument. There is always a single layer of epidermal cells lying immediately beneath the cuticle. These cells secrete the new cuticle at molting, and in some insects at least, continue to secrete cuticle even...