The native pitch twig moth is a clearwing moth species that will develop in the twigs of pine, particularly pitch pine, of the current year's growth. This difference sets them apart from other similar species in the same genus (Petrova) on similar hosts. For example, the pitch twig moth may be confused with the northern pitch twig moth (Petrova albicapitana) however that insect is known from lodgepole and jack pines. Details of the development of this insect were reported from studies completed in 1951 through 1953 in Ohio by Miller and Neiswander (1956), however this insect was described initially by Fernald in 1879 from specimens collected in pitch pine in Ithaca, NY by Professor J. Henry Comstock, to whom Charles H. Fernald dedicated the species. A single generation occurs per year, however historically there has been confusion as to whether or not two generations per year were possible. Two generations per year may occur in the southern portion of the insect's range, where it has not yet been studied. Eggs of this species are tiny, circular, and yellow when first laid by the adult female moth. Eggs hatch and caterpillars were present in Ohio by June. Early feeding by the caterpillars is completed at the needle bases for 1-2 weeks. Caterpillars molt at least once before then boring into the twigs and feeding, creating a nodule. After a month of feeding, the caterpillars move through the center of the twig and begin feeding on the pith. The feeding done by this insect causes ample resin (pitch) to leak from the initial feeding sites. Resin combined with frass form the characteristic nodule created by the activity of this insect. Nodules are typically found on the upper surfaces of the twigs. Caterpillars may work to expand these nodules using their mouthparts, moving resin, frass, and silk. Nodules formed on pitch pine are dark red-orange and those on Scotch pine are a lighter orange. During the winter, when larvae are inactive, weathering removes this coloration from the nodules. On average, these nodules are 7/8 of an inch long, but may vary from 1/2 to 1 and 1/4 inches long. At least 5 larval (caterpillar) instars may occur, however this information is not known for certain. Partially grown caterpillars overwinter with their heads positioned toward the lower end of the tunnel they create in the pith of the host plant twigs. In Ohio, by early April the caterpillars resume their activity in the spring. Once mature, the caterpillars create an exit tunnel, which enables them to pupate within their nodule, but emerge from an exit hole which causes the pupa to emerge from the nodule halfway at the time the adult moth is ready to emerge. In Ohio, pupation occurred by the end of April for a period of 4-5 weeks. Adult moths were present by May (Miller and Neiswander, 1956). Jones and Kimball (1943) found the flight period of adult moths in Nantucket and Martha's Vineyard, MA to be from approximately June 19 to July 22, at the time.
Caterpillars bore in the twigs or stems of pitch or Scotch pine, only in the current year's growth. Red pine is only an occasional host, supporting only light populations and usually only if growing near infested pitch pine. Rare records of pitch twig moths on other pines exist, but only a single specimen was collected and only when nearby infested pitch pine. Typically, host trees are not killed by this insect. However, when populations are high, the impact of the activity of this insect on current season's twigs can be of economic importance. See above for a description of the nodules created by the feeding activity of this insect on infested current year's twigs. Infested twigs may also be spotted if brown, dislodged needles are searched for. Partial or complete girdling of the twig may occur (Miller and Neiswander, 1956). Infested twigs may be more prone to breakage. Twigs under 1/8 inch in diameter are typically not infested by this insect. Twigs that survive infestation by this insect may recover and resume normal growth, however this often takes 3-4 years to happen. In the forest, nodules may not be found below 4 feet on host trees. On ornamental trees, however, nodules are present below or above 4 feet. Historically, this insect has been seen impacting nursery stock as well.
Adult moth flight activity may occur from May through June. Young larvae may be present on twigs, first feeding at the base of needles by mid-June. After that time, nodules may develop on the current season's twigs and may be observed with visual monitoring.
Vigorously growing twigs are less susceptible to the activity of this insect than those growing slowly or poorly. Vigorously growing twigs may survive supporting up to 3 caterpillars (Miller and Neiswander, 1956). Maintaining host plant health and vigor, and proper planting under the correct site conditions may help hosts weather this insect. Prune out infested twigs displaying pitch nodules in the terminals and destroy.
Agathis pini, Hyssopus thymus, and Calliephialtes comstockii are all recorded parasites of the pitch twig moth that affect the caterpillar life stage. Adult parasitoids are said to emerge at the same time as the adult moths. H. thymus is reportedly able to kill up to 7% of the pitch twig moth caterpillars by late summer. In a study comparing survival rate of pitch twig moth in forested trees vs. ornamental trees, Agathis pini was found to be a significant mortality factor in the forested tree stands, but was not present in the ornamental locations. A. pini may be an important factor keeping the pitch twig moth at low or endemic levels in forests (Miller and Neiswander, 1956). Agathis pini and Glypta varipes were both reported as parasitoids of the pitch twig moth by Schaffner (1959).
Acephate (NL)
Bifenthrin (larvae) (NL)
Chlorantraniliprole (NL)
Cyantraniliprole (NL)
Emamectin benzoate (L)
Permethrin (L)
Chemical management may not be necessary, especially on forested trees where natural enemies are present in the population.
Active ingredients that may be applied systemically include: acephate (injection), chlorantraniliprole (soil drench), cyantraniliprole (soil drench, soil injection), and emamectin benzoate (injection).
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.
