Flying adults invade from neighboring fields. Damage is caused by chewing through the succulent portion of the small stems below the bolls, with bolls dropping to the ground. Seedling feeding may be a problem in late seeded fields. Cutworms and armyworms. Larvae of one or more cutworm species are known to cut and consume the seedling at the soil level.
Damage is often severe by the time infestation is identified.
Armyworm larvae feed on foliage in midseason. Leafhoppers feed on the plant juices. This insect infects the plant with the aster yellow mycoplasm when feeding. The aster yellow disease is also observed on canola, sunflower and several broadleaf weeds. Aphid populations can increase rapidly and have been observed on flax.