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Delia coarctata, known more commonly as the wheat bulb fly is a pest of a number of crops of the Poeace family. Adults emerge in June, are dun in colour and reach a size of 8 mm (Long, 1958a), they oviposit from mid to late summer (Gough, 1946). Eggs, creamy white in colour and measuring approximately 1.3 x 0.4 mm, are laid in bare soil, fallow ground and open canopy crops, where they overwinter. Eggs hatch in late winter early spring (Way, 1959), with the first instar larvae being approximately 1.8 mm in length (Gough, 1946). Unlike other Anthomyiid flies such as cabbage root fly, Delia radicum (Baur et al., 1996) and onion fly, Delia antiqua (Judd & Whitfield, 1997), eggs are not laid in close association with a host plant, with larvae using chemical exudates from host plants, such as hydroxamic acids, to locate and indentify suitable seedlings, before entering and feeding within the stem of the plant. The damage inflicted by the larvae causes yellowing and the eventual death of the stem, a sign referred to as ‘deadheart’, the larvae pass through three instars before exiting the plant and pupating in the soil in late spring. This species is [[voltinism|univoltine through out it’s range

Economic significance
Delia coarctata is a pest of economic importance in winter wheat, barley and rye. Yield losses attributed to Delia coarctata have been recorded as high as 4 t/ha (Young & Ellis, 1996). However, economic damage is sporadic making egg monitoring for population forecasting important.