Definition: Pyrale

The vine moth is a butterfly with a wingspan of no more than two centimetres: the cycle of this lepidopteran begins in August, when the females lay thousands of eggs that will hatch two weeks later into tiny caterpillars (1 to 2 mm long). At this stage, the caterpillars do not eat: they take shelter in the various crevices of the vine, where they spin small greyish cocoons that will enable them to withstand the cold of winter. In spring, they emerge from their lethargy, begin to eat the leaves and weave a web of silk threads that hinder vegetation growth. Various methods of control have been considered: destroying the moths at night using light traps such as acetylene lamps; scrubbing the vines with metal brushes; applying insecticide coatings; covering the vines with cloches, or sulphurisation, to destroy the larvae by exposing them to sulphur gas for a certain period of time; or scalding, a process devised in 1840 by Raclet, a Burgundy winegrower, which involves destroying the moth larvae by pouring boiling water over the stumps: the boiling water is produced in boilers and distributed over the stumps using coffee pots or a rubber tube connected directly to the boiler.

The discovery of scalding was accidental. The winegrower Radet regularly threw his dishwater out of the window. One day, when all the vines were infested with moths, he noticed that the plot under his window had been spared. He made the connection and invented the scalding process.