Mealybug Biology: Honeydew, Morphology, and Metabolism

A student or researcher asked three specific questions about mealybugs on cotton plants: the chemical composition of honeydew, mealybug metabolism, and morphology.

Mealybug Honeydew Composition

Honeydew is primarily plant sap sugars excreted by the mealybug, mixed with its saliva. It's a sticky, sugar-rich substance that often attracts ants and supports sooty mold growth.

Mealybug Morphology

Mealybugs are oval, soft-bodied insects covered in a white, waxy, cotton-like secretion. They have filamentous projections around their body margins. Despite their appearance, they can jump or fly when disturbed. They are piercing-sucking insects that feed on plant phloem.

Metabolism Note

Mealybugs have a specialized metabolism adapted to a high-sugar, low-nitrogen diet from phloem sap. They rely on symbiotic bacteria to synthesize essential amino acids. Their feeding produces copious honeydew as a byproduct of processing large volumes of sap for nitrogen.