Australia
Melaleuca (Melaleuca quinquenervia)
Eggs are 1 mm long and yellow but are coated with a dark protective secretion. Early instar larvae are small and yellow while mature larvae are up to 14 mm long, grayish, and slug-like in appearance. Larvae produce long, thin coils of feces and are covered in an orangish protective oily secretion that turns dark with fecal matter. Adults are up to 9 mm long and reddish-brown initially but turn darker gray with age. They have knobby protuberances on their elytra and a stout snout.
This species reproduces year-round, resulting in multiple overlapping generations. Females lay 500–1,000 eggs singly on young melaleuca leaves and expanding buds and twigs. Larvae are specialized feeders, feeding on the seasonal flush of young melaleuca leaves through four instars. They consume all layers of leaf tissue except the cuticle, leaving “window” feeding scars. At maturity, larvae drop from the host plant to burrow into the soil for pupation. Adults feed on melaleuca leaves, buds, and stems, leaving holes and gouges in young tissue and defoliating young leaves. Adult feeding damage to tough, older leaves is often more superficial, resulting in narrow scars along the leaf surface. Adults are long-lived (over one year), and there are 2–3 generations produced per year in Florida’s climate.
Heavy larval and adult feeding causes defoliation and tip dieback, which in turn stimulate new growth that acts as a nutrient sink and reduces reproductive output. New growth is subsequently attacked by continual generations of the beetle, increasing the impact further.
Smith, M.C. and M.B. Rayamajhi. 2022. Melaleuca Biocontrol Agents: History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2022-26-MELALEUCA-A. https://bugwoodcloud.org/resource/files/25232.pdf