Pests were monitored on linseed crops in Hertfordshire, Cambridgeshire
and Bedfordshire from 1987 to 1990. Adult flea beetles (Aphthona euph
orbiae and Longitarsus parvulus) caused severe injury to seedlings; th
eir numbers have markedly increased since 1990 and they are now import
ant pests of linseed in the UK. Two generations of Thrips angusticeps
bred on linseed, causing damage to growing points and flower buds and
approximately 14% yield loss to a crop in Hampshire. Mirids, mostly Ca
locoris norvegicus and Lygus rugulipennis, caused injury similar to th
at caused by thrips. Mirids were more abundant close to field boundari
es with woody plants, whereas thrips were fewer at these boundaries an
d rather evenly distributed within the rest of the field. Few other in
sects and no aphid colonies were found. Experiments with insecticide t
reatments provided evidence of compensation for insect injury by addit
ional flower production. (C) 1997 Elsevier Science Ltd.