Agriotes lineatus (Linnaeus, 1767)
This generally common and often abundant species occurs throughout Europe, except for the far north, across to the far east of Russia, and has been introduced to New Zealand, Brazil and Canada among many other countries. In the U.K. it is common to South Yorkshire, further north it is much more local and scattered. On a global scale it is one of the most common harmful agricultural pests, the larvae are widely polyphagous and attack almost all crops, destroying seedlings and penetrating tubers etc. Adults overwinter under debris and especially among grass tussocks, they fly well and are active from the first warm days in March, by May and June they are common and will generally persist into August. They occur in a wide range of habitats including grassland of all types, woodland, wasteland and gardens, and may be swept from vegetation generally but more particularly from grassland and arable situations, in warm weather they visit a range of flowers, especially apiacaea. Mass flights occur in May and June when the adults move from winter to summer habitats. Oviposition occurs in moist soil in May and June when each female will produce 75-150 eggs. They hatch within 2-4 weeks and the larvae feed on roots and tubers etc. for up to four years, burrowing from plant to plant and sometimes ascending the stems to feed, especially in potato crops. They generally inhabit open and disturbed soils but will tolerate land with a high water table that is subject to occasional flooding, they will tolerate long periods without food but moisture is essential. Some plants e.g. linseed and flax seem to be immune to attack. The larvae are typical ‘wireworms’, up to 25mm long and 2mm wide, with tough pale cuticle darkened at the segment margins and the head, and with robust and toothed mandibles. Pupation occurs in a cell deep in the soil in late summer and the adults eclose within 2-4 weeks giving rise to an autumn generation that will overwinter. The entire life cycle takes 4-5 years.
The species is easily recognized by the alternately light and dark brown elytral interstices, a character that varies but is readily appreciated in the field. Size 7-10mm. The entire body is various shades of brown, with pale appendages, the dorsal surface with short grey or yellow pubescence. The antennae are filiform; the second segment as long as the fourth. Head very dark, sometimes black, and broad compared with the anterior margin of the pronotum. The pronotum is elongate and broadest in front of the middle. The elytra have strongly punctured striae and finely cross strigose interstices. The claws simple, not serrate.