The pine needleminer is a native species of moth for which pitch pine is a primary host, but others may be fed upon as well. On occasion, this native insect can be a serious defoliator of its hosts in the eastern United States and parts of Canada. The eggs of this insect are laid in the spring and once they hatch, caterpillars crawl to a new needle to enter the flat side to feed. The caterpillars of this species are tiny, and the entrance hole created by the caterpillar may become filled with pitch (resin) and difficult to find. Caterpillars feed until the second instar, leave the first needle, and enter a new, not yet mined, needle to continue feeding. The caterpillar will feed and overwinter in the second needle it selects. In the springtime, overwintered caterpillars mine to the base of the needle, emerge through a round exit hole, to enter a third needle. At maturity, caterpillars are 6 mm long, with a brown body, and a dark brown head and prothoracic shield. At least four larval instars are recorded for this species. Mature caterpillars pupate in the third and final needle. Mature caterpillars may be present from April through June. A single generation occurs per year. At least five additional species of needleminers are found on pine in North America.
Caterpillars mine the needles of their hosts, typically killing one needle per pair that is fed upon. The mined needles turn brown and die. This native insect is typically not a problem in the landscape, but can affect plant aesthetics when in nursery production or on Christmas trees for sale. May be more common in coastal areas of New England, but also found inland.
Visually monitor for browned needles on susceptible hosts in the spring. Magnification will be needed to see tiny entrance holes filled with resin. If possible, dissect a sample of browned needles under magnification to search for caterpillars or pupae, depending upon the time of year.
This insect is typically a minor pest of ornamental trees and cultural management options are not fully understood at this time.
Native natural enemies exist for the pine needleminer and are thought to typically keep populations below damaging levels in ornamental landscapes. Finnegan (1965) notes that three parasitoids of the pine needleminer impact its populations. Achrysocharis spp. (approximately 8% mortality), Copidosoma spp. (approximately 3% mortality), and Dicladocerus spp. (approximately 3% mortality) cause some mortality of pine needleminers. This was based on studies of pine needleminer larvae in 1962. Further details about the natural enemies of the pine needleminer have been difficult to find. Hymenopteran parasitoids of the pine needleminer are listed by Schaffner (1959) from collections in Maine and Massachusetts. These include: Alegina pinifoliae, Apalantes spp., Apalantes paralechiae, Chelonus spp., Closterocerus tricinctus, Copidosoma spp., Derostenus silvia, Eulophus spp., Habrocytus spp., Haltichella xanticles, Horismenus microgaster, Pimplopterus parvus, Spilochalcis side, Sympiesis guttatipennis, Tetrastichus marylandensis, and Zagrammosoma interlineatum.
Finnegan (1965) also notes that strong winds and rains during the period of adult flight, mating, and egg laying may reduce the population noticeably and this was observed in the field in 1963 (Quebec).
Abamectin (NL)
Acephate (NL)
Acetamiprid (L)
Bifenthrin (NL)
Chlorpyrifos (N)
Cyantraniliprole (NL)
Emamectin benzoate (L)
Flonicamid+cyclaniliprole (N)
Horticultural oil (L)
Insecticidal soap (NL)
Malathion (L)
Neem oil (NL)
Pyrethrin+sulfur (NL)
Spinosad (NL)
When used in a nursery setting, chlorpyrifos is for quarantine use only.
Active ingredients that may be applied systemically include: abamectin (injection), acephate (injection), acetamiprid (injection), chlorantraniliprole (soil drench), emamectin benzoate (injection), and neem oil (soil drench).
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.