Another lawn pest, these larvae of Crane fly or “Daddy Long Legs” are grey-brown cigar-shaped grubs which develop under the grass in late August/September. They overwinter there until they stop feeding in mid-May to pupate, emerging as the leggy adults we know in August.
From August until mid-May they are eating the roots of your lawn, resulting in brown tufty patches, resembling Chafer damage, but looking its worst in March/April. Small infestations are not troublesome, but more than 20-25 grubs per sq.ft. becomes a problem.