WIREWORMS are undoubtedly the most notorious of all insects of agricultural importance, probably because their depredations are more extensive at times of agricultural expansion and prosperity. The traditional agriculture of Britain has been mainly the type known as 'mixed farming', and the measure of prosperity has been the extent of land under the plough. Wireworms are grassland insects, and so long as grassland is undisturbed they are of no economic importance. Periods of agricultural depression are periods of increasing areas of grassland, both cultivated and derelict, and consequently periods in which the numbers of grassland insects increase. Events that lead to high prices for cereals—the Napoleonic wars and the Corn Laws in the first half of the nineteenth century, and the German wars in the twentieth century—are associated with the ploughing up of grassland, and the enhanced value of the crops stimulates the interest of the farmer in the causes of crop failure. It is a simple proceeding to pull up dying plants, and only too frequently the expected wireworms are found at their roots.