The Balearic ministry of agriculture and fisheries has announced that it will commence spraying from the air to combat the processionary plague in pine trees tomorrow, providing weather conditions are favourable. The spraying will affect various municipalities in Majorca and Minorca. Spraying is one of the methods used to attack the plague caused by the processionary moth which lays its eggs in the pine trees. The caterpillars emerge from their nests at night to feed on the tender green needles. They weaken the tree which is then prone to diseases which eventually cause it to day. Spraying is used on large areas of trees where the plague is prevalent and where other methods of treatment are not suitable. The products used for spraying are harmless to man and fauna but, the ministry says, are very efficient against the processionary plague. Other methods used are sexual lures, which use pheromones to trap the male moths, shooting down the nests or chopping off the branches with nests and burning them. The agriculture ministry provides the lures and cut-price shotgun cartridges. The nests and the caterpillars can produce painful rashes and should not be touched. The plague is difficult to eradicate completely because the chrysalis can remain underground for more than a year, before emerging as moths and starting the cycle again.