Red Palm Weevil

• By the time the visible symptoms appear, with the central leaves drooping or the crown collapsed, the palm is usually already lost: the larvae have been at work inside it for months.
• One early-detection technique is to listen inside the trunk with acoustic sensors, because the sound of the larvae chewing is audible with the right equipment.
• It has transformed the townscape of many Mediterranean cities and forced the felling of century-old palms all along the Spanish coast.
• It reached Spain in 2005 and has killed tens of thousands of palms, above all Canary Island date palms and date palms, along the entire Mediterranean coast.
• The damage is invisible until it is irreversible: the larva feeds on the inside of the trunk and the heart of the palm, and by the time the crown begins to droop the tree can no longer be saved.
• A single palm can harbour hundreds of larvae at once.
• It spread through the trade in transplanted adult palms, which travelled from one country to another already infested.
• It is detected with traps baited with aggregation pheromone combined with plant bait, and also with acoustic methods: microphones that pick up the sound of the larvae gnawing inside the trunk.
• In the Canary Islands its arrival amounted to a plant-health emergency because of the risk to the Canary Island date palm, which is endemic and a symbol of the archipelago.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Palms, especially Canary Island and date palms

Size at birth

Creamy white egg, glossy and oval; the larva is legless and pear-shaped, with a brown head and thirteen segments, and bores galleries that can reach a metre

Sexual maturity

The final-instar larva pupates inside an elongated cocoon made of fibres from the palm itself, and the adult stays inside it for about another ten days before leaving

Gestation / incubation

The eggs hatch between 1 and 6 days; larval development lasts 40 to 60 days (84.6 on an artificial diet) and the pupa 20 to 30 days; the full cycle closes in 70-120 days

Litter / clutch size

More than 200 eggs per female over a life that can exceed four months; in the laboratory a mean fecundity of 211 eggs per female was measured. They are laid one by one in holes the female bores with her rostrum at the base of the palm fronds

Sources consulted: https://es.wikipedia.org/wiki/Rhynchophorus_ferrugineus; Bio-ecologia del picudo rojo (Generalitat Valenciana); estudio de cria en dieta artificial (Universidad de Almeria); Sistema Nacional de Vigilancia y Monitoreo de plagas; estudios de cria del picudo rojo en Espana; Koppert; Koppert, ficha Picudo rojo

Best time: The symptoms are not apparent until months after colonisation, by which time the palm is already severely damaged; in the Mediterranean basin its preferred host is Phoenix canariensis