Sugar-cane borer

It is the larva of Nonagria sacchari, an insect of the order Lepidoptera. As early as 1502 this larva was devastating Madeira’s sugar plantations: on 15 November of that year a royal letter (carta régia) was sent to the judges and councillors (vereadores) of the Funchal Municipal Council (Câmara Municipal do Funchal), recommending the use of ash to destroy the cane borer. On 29 June 1509 a further royal letter announced the arrival on this island of one Fernão Rodrigues, charged with providing a remedy ‘to kill the grub that infests the canes... from which so much loss and damage follows’, and recommending that this Fernão Rodrigues be lodged and rewarded as the services he came to render deserved.

Despite these measures, it was only around 1887 that the cane borer began to disappear, owing to the relentless war waged on it by Iridomyrmex humilis, a species of ant imported from Demerara. Before this ant was introduced to Madeira, purely by chance, growers used to light torches and walk with them at night through the land planted with cane, so that the insect would fall onto the flame and die.

The larva of Nonagria sacchari lives inside the cane stalks, where it bores galleries that open to the outside. The walls of the galleries harden, and the adjacent tissues turn reddish and quickly begin to ferment. It appears mainly in summer, but since the introduction of the ant it has been rare on the island of Madeira.