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Euopean pine shoot moth damage often appears as stunted shoots or buds that simply do not break in the spring.

European Pine Shoot Moth

The larvae and pupae (above) are often found in the dead buds in June.

Species: Rhyacionia buoliana (Dennis & Schiffermuller)


Distribution: Europe and most of northern North America, especially the northeastern states.


Hosts: Most hard pines, especially red, mugho, Scotch and Austrian.


Damage:

The young larvae kill small buds which is soon noticed when they do not expand in the spring. During the spring feeding, the larvae enter and kill larger expanding shoots, causing them to wilt and soon turn brown. If all of the leader buds are attacked, a lateral curls around to take its place, forming a permanent crook or "post horn." Heavy infestations result in rounded trees with very stunted growth.


Description and Life Cycle:

The adults and larvae of this pest are usually not seen but their damage, wilting or dead shoots, is very noticeable. This pest overwinters as partially grown caterpillars hibernating in silk-lined cavities eaten into pine buds. In late April, when the pine shoots begin to expand, the larvae resume their habit of boring into shoots. The larvae may move from one shoot to another, usually entering at the base. The entrance holes are covered with silk webbing coated with pine pitch. The larvae finish development at the end of May and soon form a pupal cell within one of the tunneled shoots. The rust colored adult moths emerge two to three weeks later. The 3/8-inch moths mate on the pines and females soon lay eggs on needle bases, bark and bud scales. The eggs hatch in seven to ten days and the tiny caterpillars burrow into needle bases. By August, the young larvae move to the newly formed pine buds. Here they burrow into a bud and construct a resin coated web over the entrance hole. By the end of August, the larvae cease activity, remaining dormant until the next spring.


Control Hints:

Since the larvae are first needleminers and then shoot borers, they are generally protected from contact sprays. Thus, timing of controls is very important so as to catch the larvae when they move from one bud to another.

Option 1: Cultural Control - Delay Sheering - Since the young larvae are concentrated on the branch tips, pruning will effectively remove them from the trees. Most sheering operations remove enough larvae that sprays are unnecessary. Try to delay sheering until mid to late July.

Option 2: Chemical Control - Summer Sprays - The larvae move from the mined needles to buds in late July and early August. Sprays applied at this time will kill a good number of the larvae. Pheromone traps have been developed for this pest and timing of sprays can be made by monitoring the adult flight. Spray susceptible trees about 10 days after the peak adult catch has occurred.

Option 3: Chemical Control - Spring Sprays - Time sprays to kill the larvae as they move from bud to bud. This activity is usually most common in early to mid-May. Systemic insecticides will kill more larvae since actual contact with the feeding caterpillars is not necessary.