European Pine Shoot Moth Larva

These are moths whose larvae cause severe damage to the new growth in select pines. Three different types of damage may occur on shoots anywhere on the tree: newly hatched larvae can kill individual needles, particularly around buds; intermediate larvae kill buds in preparation for overwintering; and mature larvae kill developing buds and elongating shoots. Damage by the mature larvae, which occurs in spring, is the most significant and results in production of numerous adventitious buds, leading to a type of witches’-broom. As a result of European pine shoot moth feeding, trees will have dead, stunted shoots. Shoots that are damaged, but not killed, will continue to grow into a characteristic “S” shape, known as a post horn. Infested trees are frequently bushy and distorted and may develop multiple leaders, which require intensive corrective pruning to restore a desirable shape. Detection of this pest may be difficult. In late summer or fall, look for resinous masses concealing single larvae inside hollowed-out buds. In spring, scout for dying buds and shoots containing larvae. Pruning out infested buds is time consuming but effective. Spray treatments can help if carefully timed. Soil treatments are very effective.