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How to identify it
- Adults are buff-colored moths with a wingspan of about 1 inch. The female's abdomen is dark on the underside; males look similar but are slightly smaller with a light yellow underside.[1]
- The larva is a green to greenish-yellow caterpillar about 4/5 inch (almost 1 inch) long when mature and very active when disturbed, wiggling and dropping quickly from the tree on a silken thread.[1]
- Egg masses are flattened clusters of about 30 eggs laid in branch forks and bark crevices and covered with scales from the female's body, which makes them hard to detect.[1]
- Feeding sign starts as webbing along leaf folds and veins with the tissue between the veins eaten out, then individual leaves rolled or several leaves webbed together; the Forest Service describes the species as skeletonizing and rolling boxelder leaves.[1][2]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Fruittree leafroller | Another Archips leafroller of trees; the boxelder leafroller is identified by its host, feeding mainly on boxelder, with the buff moth flying late June through July in northern Utah.[1][2] |
| Adoxophyes negundana | An uncommon, solitary leafroller on boxelder in Manitoba, Saskatchewan and Alberta, whereas young Archips negundana larvae feed in small groups and can defoliate trees.[2][1] |
| Uglynest caterpillar | A related Archips whose larvae live in dense, frass-filled silk nests on cherry rather than in individually rolled boxelder leaves.[2] |
Where it lives
A pest of boxelder and other trees and shrubs in parts of the United States and Canada and common in Utah; the Forest Service records it in Nebraska, Utah, Idaho, Washington, Manitoba, Saskatchewan and British Columbia and also lists it among the Archips of eastern forests.[1][2][3]
Biology and life cycle
The boxelder leafroller overwinters as eggs in cracks and crevices of the bark. The eggs hatch soon after budbreak, and the young larvae crawl to the developing leaves and feed in small groups.[1][2]
As they mature the larvae disperse and feed singly in leaves they have rolled with webbing. Development is usually complete by mid-June, and pupation in the rolled leaves or in bark crevices takes about two weeks.[1]
In northern Utah the moths fly from late June through July. Females lay flattened masses of about 30 eggs in branch forks and bark crevices, and those eggs do not hatch until the following spring, so there is one generation a year.[1][2]
Damage and signs
- Young larvae form webs along leaf folds and veins and eat the tissue between the veins; older larvae roll individual leaves and may web several together. Heavy infestations can completely defoliate a tree by early to midsummer.[1][2]
- Boxelder trees produce a second set of leaves when the first is removed, so a tree stripped early in the season may look nearly normal by the end of summer. A well-established, unstressed deciduous tree can usually withstand about 30 to 35 percent leaf loss before its food reserves suffer, and established boxelders completely defoliated three years in a row have continued to live and grow normally.[1]
Health risk
The sources treat the boxelder leafroller only as a pest of trees and shrubs and mention no effect on people.[1][2]
Control
Prevention
Control is usually unnecessary: this native species normally occurs at low populations, and even completely defoliated boxelders releaf and recover. Treat only to protect a young tree's health or the shade and appearance of a valued mature tree.[1]
If treatment is wanted, apply the insecticide in spring as soon as leaf damage or larvae are detected. Hose-end sprayers with good water pressure reach trees up to about 30 feet; larger trees need power equipment, which may cost more than the tree is worth to the owner.[1]
Pesticides
Organic options labeled for leafrollers on boxelder, maple or ornamental shade trees contain Bacillus thuringiensis (aizawai or kurstaki strains) or spinosad; the caterpillar must eat them and they work only on larvae a half inch or less. Conventional options are carbaryl, malathion and pyrethroids, which work on all sizes. Check that the label lists the tree or ornamental shade trees in general.[1]
Common questions
- My boxelder lost all its leaves in June. Will it die?
- Probably not. Boxelders produce a second set of leaves after defoliation and often look nearly normal by late summer; established trees defoliated three years running have kept growing normally.[1]
- When should I spray for boxelder leafroller?
- Only if you decide the tree needs protecting, and then in spring as soon as you see leaf damage or larvae; Bt and spinosad work only on caterpillars a half inch or smaller, so timing matters.[1]
- How does the boxelder leafroller survive winter?
- As egg masses of about 30 eggs hidden under the female's scales in branch forks and bark crevices; they hatch soon after budbreak, giving one generation a year.[1][2]
Sources
- Utah State University Extension, “Boxelder Leafroller, Utah Pests fact sheet (M. Murray and R. Davis, July 2023).” extension.usu.edu/planthealth/research/boxelder-leafroller (accessed 2026-11-10)
- USDA Forest Service, “Western Forest Insects, Miscellaneous Publication 1339 (R. L. Furniss and V. M. Carolin, November 1977; scanned copy).” archive.org/details/CAT78702369 (accessed 2026-11-10)
- USDA Forest Service, “Eastern Forest Insects, Miscellaneous Publication 1175 (W. L. Baker, 1972; scanned copy).” archive.org/details/easternforestins1175bake (accessed 2026-11-10)
- iNaturalist, “Archips negundana taxon page (order and family).” www.inaturalist.org/taxa/214083 (accessed 2026-11-10)