There is a complex of at least 10 species that are sometimes collectively referred to as "fruitworms" or "green fruitworms". These are native insects that feed on similar hosts at the same time and cause similar feeding damage. One generation is reported per year. Often, Lithophane antennata is the species that is referred to as the "green fruitworm". The adult moth stage overwinters in sheltered areas after becoming active in September and November. The following spring, they become active again when temperatures are above 60F. Adult moths mate and females lay eggs singly or in masses. Adults are light brown in color and approximately 1 inch in length. Eggs hatch and young larvae crawl to the opening buds of their host plants and begin to feed, usually beginning around April or May in Massachusetts. Caterpillars mature as the leaves of their host plants mature. Fruitworm caterpillars are often pale green with faint white stripes along the length of their bodies and can be up to 1.25 to 1.5 inches in length at maturity. Larvae have six instars (molting in between each) and once mature, they move to the soil to pupate. Fruitworm caterpillars may be observed feeding on their hosts until approximately the end of June. Other commonly reported species of fruitworm in the eastern US include Orthosia hibisci and Amphipyra pyramidoides.
Because fruitworms begin feeding so early in the season, they are capable of destroying the buds of their host plants. Their feeding eventually produces tattered foliage. However, these native insects do not always cause noticeable damage to their host plants, and often are found in low populations that are not damaging. In ornamental settings, the feeding activity of these insects may not be significant enough to warrant management, unless it is a particularly high population year. The largest issue regarding fruitworms is for the apple and stonefruit industries. For example, in apple, certain species of fruitworm feeding damage may cause many apples to abort or if they do mature to harvest, they may have deep corky scars and indentations (but this depends upon the species of insect).
Scout susceptible host plants beginning in April and May in Massachusetts for defoliation caused by caterpillars. Fruitworms are considered sporadic pests, and low populations can be tolerated, so management is often not necessary unless population outbreaks are reported.
If few caterpillars are found, remove them from ornamental plants by hand where practical.
Certain parasitic wasps (Apanteles, Eulophus, Meteorus, and Ophion spp.) are reported in fruitworm populations and may help prevent noticeable damage in managed landscapes (UC IPM Pest Management Guidelines, 2017). However, natural enemies are not reported to be significant enough in their impact on fruitworm populations in orchards.
Abamectin (NL)
Acephate (NL)
Acetamiprid (L)
Azadirachtin (NL)
Bacillus thuringiensis subsp. azawai (L)
Bacillus thuringiensis subsp. kurstaki (NL)
Beauveria bassiana (NL)
Bifenthrin (NL)
Chlorantraniliprole (NL)
Chlorpyrifos (N)
Chromobacterium subtsugae (NL)
Cyfluthrin (NL)
Cyantraniliprole (NL)
Deltamethrin (L)
Emamectin benzoate (L)
Flonicamid+cyclaniliprole (N)
Gamma-cyhalothrin (L)
Horticultural oil (L)
Indoxacarb (L)
Insecticidal soap (NL)
Malathion (L)
Methoxyfenozide (NL)
Neem oil (NL)
Permethrin (L)
Pyrethrins (L)
Pyrethrins + piperonyl butoxide (L)
Spinetoram+sulfoxaflor (N)
Spinosad (NL)
Tau-fluvalinate (NL)
Tebufenozide (NL)
Zeta-cypermethrin (L)
Active ingredients that may be applied systemically include: acetamiprid (injection), azadirachtin (injection, soil drench), chlorantraniliprole (soil drench), cyantraniliprole (soil drench, soil 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.