Between 10 and 15 per cent of the lowland wheat-growing area has been damaged by the orange blossom midge, a rare pest not seen in such numbers in the UK for probably half a century.
The reduction in wheat yields is estimated at between 2 and 5 per cent; on some farms it is up to 30 per cent. Agricultural scientists are at a loss to explain the outbreak. However, the warm, dry weather at the end of June, when the ears on the wheat begin to form was crucial, enabling the midges to lay eggs in the wheat kernels.
The midge, 2mm long, can lie in the soil in pupa form for up to 20 years. Warmer and wetter weather earlier in the season has been advanced as a reason why it has emerged in numbers not seen in some areas for up to a century.
The Ministry of Agriculture said it was 'just one of those things'. Alternative hypotheses link it with climate change caused by global warming and the increase in agricultural 'set aside', land taken out of production which may act as a source of pests and crop disease.
As the larva eats the wheat grain from the inside, it is not easily detectable. By the time it was spotted, in a swathe along the south and east coasts from Wiltshire to Yorkshire, it was too late for spraying.