Een studie over emelten en hare bestrijding

After a survey of the literature since 1602 on leather-jackets in agriculture, systematic and biological features are discussed of species important for the Netherlands. Next follow questions of more direct agricultural importance. The excreta and the intestinal content could not derive much from humic sand, as microscopical scrutiny showed little silica in the gut. Leather-jackets would only eat humic sand if food was scarce. Living or dead plant material was their food. Although attacking many plants, they sometimes showed preference, as for white clover over grass. The author observed more injuries on stalks and leaves above or just under the soil surface than on roots.
The larvae attacked practically all Gramineae, many field and garden crops (incl. flowers) and sometimes seedling trees. The adult crane-fly however preferred grass and clover land, and there laid its eggs, so that meadows were most attacked. The larvae were hardly harmful during their first instars, considerably harmful in the 3rd instar, and most in the 4th (usually in spring). The larvae of Tipula maculata, T. vernalis and of the T. oleracea-group pupated by the beginning of May but those of T. paludosa still fed in May, June or even in July. Feeding stopped 8 to 14 days before pupation. The intestinal canal then largely emptied. After a discussion of influences on the numbers of leather-jackets, control measures are critically reviewed.