On this page
How to identify it
- The adult is a slender moth only 1/8 to 1/5 inch long. Its forewings are golden brown or golden bronze with white bands edged in black, its gray hindwings have long fringe hairs, and it holds its wings roof-like over the body at rest.[1][2]
- Young larvae are legless and cream-colored; older ones have legs and are cylindrical, and mature larvae are yellow and about 1/6 inch long.[2]
- The mine starts as a blotch visible only from the underside of the leaf. Later the larva feeds just under the upper surface and spins silk that pulls the mine together into a puckered, tent-like shape.[2]
- Eggs are tiny, round and flat, transparent when first laid and turning yellowish green; they are hard to see without magnification.[1][2]
Where it lives
It is a leaf-mining pest of apple orchards in the Pacific Northwest and Utah.[2][1]
Biology and life cycle
It mines the leaves of apple and cherry, and Utah State University also lists prune as a host.[1]
It spends the winter as a pupa in fallen leaves. Adults emerge early in the season and lay eggs on the undersides of leaves around the time apple flower buds show pink.[2]
The larva passes through five stages. The first three feed on the soft, spongy tissue inside the leaf; by early to mid-May larvae begin feeding under the upper surface and tie the mine together with silk. Larvae of the first generation pupate inside the leaf.[2]
There are three to four overlapping generations a year.[2]
Damage and signs
Health risk
These orchard guides treat it only as a plant pest and do not describe any harm to people.[1][2]
Control
Prevention
Avoid broad-spectrum insecticides when you can: leafminer problems may follow when they kill off the parasitic wasps.[2]
Biological control
Parasitic wasps are the main control. At least six species attack leafminers in the Northwest, several are common in Utah orchards. Parasitism can reach 90 percent, enough to remove the need for sprays even where populations were once high. One small wasp, Pnigalio flavipes, controls it well enough that insecticides are rarely needed.[1][2]
Pesticides
Spray only when treatment thresholds are exceeded, generally in the second or third generation. Early sprays aimed at the first generation are recommended only if many moths are seen in April or May, or eggs average more than three per leaf from tight cluster to pink. If a spray is needed, time it after a generation's eggs have hatched and before the older tissue-feeding larvae appear.[1][2]
In commercial orchards, sprays at the prepink and tight cluster stages may create mite problems, so it is usually best to wait for the second generation.[2]
How parasitic wasps attack it
The wasps lay their eggs inside the mine, on the outside of the leafminer larva. The wasp larvae hatch and eat the developing leafminer.[1]
Common questions
- What are the puckered blotches on my apple leaves?
- They may be western tentiform leafminer mines. The larva feeds inside the leaf, first as a blotch seen from below and later as a silk-tied, tent-like mine on the upper side.[2]
- Should I spray for leafminers on my apple tree?
- Usually not. Naturally occurring parasitic wasps often control them so well that insecticides are rarely needed, and broad-spectrum sprays can make leafminer problems worse by killing those wasps.[2][1]
Sources
- Utah State University Extension, “Western Tentiform Leafminer (IPM pest page).” extension.usu.edu/planthealth/ipm/notes_ag/fruit-west-tent-leafminer.php (accessed 2026-11-09)
- Pacific Northwest Pest Management Handbooks (Oregon State, Washington State and University of Idaho Extension), “Apple-Leafminer: western tentiform leafminer (Pacific Northwest Insect Management Handbook).” pnwhandbooks.org/insect/tree-fruit/apple/apple-leafminer (accessed 2026-11-09)
- iNaturalist, “Phyllonorycter elmaella taxon page (order and family).” www.inaturalist.org/taxa/1021373 (accessed 2026-11-09)