Multiple small moths in the same genus (Rhyacionia) are pests that tunnel the tips of pine shoots in multiple areas of the United States. In the eastern US/Northeast, the historically most important three of these species include the European pine shoot moth (Rhyacionia buoliana), the Nantucket pine tip moth (R. frustrana), and the pitch pine tip moth (R. zozana). Each of these species cause similar damage to the host plants they impact, mainly that the tips of terminal and lateral branches may be killed by the boring activity of the larvae or caterpillars. A single generation of this species is known to occur per year. Adults are roughly 3/8 inch in length and have orangish colored wings that are marked with irregular, silver colored bands. Adult moths lay flat, tiny eggs on new shoots near the base of needles or bud scales in the late spring. This egg laying period may last for a few weeks. Eggs hatch and the larvae bore into the needle sheaths and mine the needles, beginning at or near the base. The yellowing of the tips of twigs or the clear deposits of pitch between new bud clusters may be early signs of activity of this insect. Mined needles will die and turn brown in color, which can be noticed in the summer. Initial areas of wounding are covered with resin-coated webbing. By the middle of the summer, the larvae move to the buds and burrow into them. Scarring is often caused. In August, feeding stops and tiny, black caterpillars overwinter in this area covered by the resin-coated webs. Mature larvae are approximately 3/4 inch in length and dark brown in color with a black head and black thoracic legs. Pupae are brown in color and pupation occurs by the following June when adults emerge to lay eggs. The European pine shoot moth was first detected in the USA in 1914 in New York and has since spread.
The larval stage of this insect is the most damaging. Caterpillars damage and/or kill the buds and shoots of the hosts. Terminal and lateral twigs may be impacted. This species can be a serious pest in nurseries and Christmas tree plantations. Host plants are not typically killed by this insect, but it can significantly alter the appearance of the plants. Caterpillars initially feed at the base of needles or buds, eventually moving into the shoot itself as they mature. Repeat infestations of trees result in plants that are distorted and historically termed "unmarketable". Trees under 10 feet tall grown in open landscapes are often most susceptible.
Monitor for "post horns" or terminals that have bent abnormally due to the activity of this insect. The yellowing of the tips of twigs or the clear deposits of pitch between new bud clusters may be early signs of activity of this insect. Initial areas of wounding are covered with resin-coated webbing. Mined needles will die and turn brown in color, which can be noticed in the summer. Pheromone traps may be commercially available for this species and can be helpful when monitoring.
Prune out and destroy dead buds and dying shoots prior to June, before pupation occurs and the next generation adults emerge. Hosts labeled as "preferred" above may be more preferentially attacked in comparison to the others listed. If possible, select lesser preferred hosts in areas where this insect is known to be a problem. Drought conditions and poor soil conditions may encourage infestations of this insect. Manage the site accordingly to reduce additional plant stress which European pine shoot moth might find attractive.
Many parasites are reported for the European pine shoot moth as well as the other tip and shoot moths in the genus Rhyacionia. Species reported in the United States include but are not limited to: Actia nudibasis, Campoplex borealis, Campoplex multicinctus, Campoplex mutabilis, Copidosoma geniculatum, Ephialtes sagax, Exeristes ruficollis, Lypha dubia, Orgilus obscurator, Pimpla contemplator, Pristomerus vulnerator, Scambus buolianae, Sinophorus rufifemur, and Temelucha interruptor. Biological control programs began in the US as early as 1928 and continued for many years. One of the most effective parasitoids of the European pine shoot moth that was released in the US (from Europe) is Orgilus obscurator. Natural enemies and biological control organisms often effectively keep populations of this insect below damaging levels. Nursery plants and Christmas tree plantations, or hosts grown on stressful, open site conditions may be the most impacted.
Abamectin (NL)
Acephate (NL)
Azadirachtin (NL)
Carbaryl (L)
Chlorantraniliprole (NL)
Chlorpyrifos (N)
Cyantraniliprole (NL)
Emamectin benzoate (L)
Lambda-cyhalothrin (L)
Malathion (L)
Pyrethrins + piperonyl butoxide (L)
Active ingredients that may be applied systemically include: abamectin (injection), acephate (injection), azadirachtin (injection, soil drench), chlorantraniliprole (soil drench), cyantraniliprole (soil drench, soil injection), and emamectin benzoate (injection).
When used in nurseries, chlorpyrifos is for quarantine use only.
Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.
Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.
