A book published in 1985 by John Turner highlight’s some of the pest problems suffered by this crop. Other work carried out between 1987 and 1990 in the counties of Hertfordshire, Cambridgeshire and Bedfordshire found that adult flea beetles (Aphthona euphorbias and Longitarsus parvulus) were important pests of this crop.
During the three years of study there were several cases of significantly higher numbers of flea beetle feeding symptoms on plants grown at the lower plant densities compared to medium and high densities.
I do not know which one this chap is in the photo but suffice to say he and his mates have found their way in to one or two of the crops of linseed that I regularly walk.
Any good at seedling weed identification? Four here to identify.