Citrus leafminer
Citrus leafminer is a very small, silvery-white moth whose caterpillars tunnel through young citrus leaves. They leave shallow, silvery, winding mines with a thin dark line of frass down the middle, and the leaves curl and twist. It attacks only tender new flush; hardened leaves resist it. The damage looks worse than it is. UC IPM states that trees older than about four years generally tolerate the damage with negligible effect on growth or fruit yield. On those trees the recommendation is to leave it alone, and let native parasitic wasps and predators eat and parasitise the larvae. Very young trees are the ones worth protecting, and only during the flushes.
Phyllocnistis citrella mines, with the dark frass line, on a young citrus leaf. Photo: pending.
Identification
Adults are less than 0.12 inch (2 mm) long, with a wingspan of about 0.25 inch (4 mm), and have silvery, white, iridescent forewings with brown and white markings. The caterpillar, up to about 3 mm long and translucent greenish-yellow, lives only inside the mine.
The mines are the thing to recognise: shallow, silvery, serpentine tunnels on young leaves, with a thin dark frass line down the centre. UC IPM uses that line to tell it from the citrus peelminer. The larva pupates inside the mine, and the leaf curls around it.
Easily confused with
- Citrus peelminerAlso a pestMines fruit and stems rather than leaves, and leaves no frass trail. Citrus leafminer mines have a thin dark line of frass down the middle.
Damage symptoms
The larvae feed just under the skin of young leaves, which curl and look distorted. On young trees heavy mining can slow growth, but UC IPM says they are unlikely to die even when heavily infested. On mature trees the effect on growth and yield is negligible, because the canopy is dense and most leaves have hardened off. In Florida and other regions with citrus canker, the mines matter more: UF notes that they open the leaf to the canker bacterium. Citrus canker is not found in California.
- Silvery, winding trails on young leaves, with a dark line down the middle
- Curled, twisted and puckered new leaves
- Damage on the newest flush; hardened leaves are spared unless numbers are extremely high
- Mealybugs sheltering in the curled leaves
Lifecycle & degree days
Development is fast: 2 to 7 weeks from egg to adult by UC's figures, and in Florida a new generation about every three weeks. Development is quickest at 70–85 °F with humidity above 60%. The number of moths follows the flushes of new growth, since that is the only place they can lay. In California, the moth is active from midsummer through autumn and early winter, and most abundant when trees flush in summer and autumn. They stay higher in coastal areas, while inland summer heat suppresses them. The pest reached Florida in 1993 and California, from Mexico, in 2000.
- Egg to adult
- 2–7 weeks, by temperature
- Generation (Florida)
- About every 3 weeks
- Optimum
- 70–85 °F (21–29 °C), >60% RH
- Active (California)
- Midsummer to early winter
Host crops
All citrus, including oranges, lemons, limes and tangerines. UF also lists orange jasmine (Murraya paniculata), trifoliate orange (Poncirus trifoliata) and other relatives in the citrus family. What matters is the age of the leaf, not the variety. Only soft new flush is attacked, so a tree that flushes over a long season is exposed for longer.
Monitoring & action thresholds
UC IPM: insecticides are generally not needed on mature trees, and are for nursery trees and plantings less than 4 years old. The one exception UC names is coastal lemon orchards, which flush repeatedly. No numeric threshold is published for home trees.
Watch the new flush, not the old leaves: only tender leaves are mined. Pheromone traps are sold and show when moths are flying and laying, but they catch only males and do not control the pest. They are a timing tool for anyone treating young trees.
Biological control
Citrus leafminer is held down by wild natural enemies, and the advice for mature trees is to let them work. UC IPM names tiny, non-stinging parasitic wasps, Cirrospilus and Pnigalio species, and says parasites control it fairly well worldwide, but are not yet uniformly present or active in every part of California. In Florida, UF reports that natural enemies already present caused up to 90% mortality of larvae and pupae. The introduced parasitoid Ageniaspis citricola accounted for up to 30% of it, mostly later in the year. Broad-spectrum sprays kill them, which is why UC IPM advises against malathion, carbaryl and pyrethroids here.
Cultural controls
Most of the useful control is about managing flush, the soft new growth the moth needs.
- On mature trees, do nothing: spray nothing, and let the new leaves harden off
- Do not prune live branches more than once a year
- Remove water sprouts
- Time nitrogen fertiliser away from the periods when leafminer numbers are high
- Do not use broad-spectrum insecticides such as malathion, carbaryl or pyrethroids; they kill the parasites and predators
Chemical, last resort
- SpinosadHome use: see label
- Azadirachtin (neem)Home use: see label
- Horticultural oilREI 12 h (farm); home: until dry
- Imidacloprid (soil)REI 12 h (Admire Pro)
Sources
UC IPM Pest Notes 74137, Citrus Leafminer (Grafton-Cardwell et al., 2010)
UC IPM Pest Management Guidelines: Citrus — Citrus Leafminer (text updated 2025)
UC IPM Citrus PMG, Selectivity of Insecticides and Miticides (2022)
UF/IFAS Featured Creatures, Citrus Leafminer (Heppner & Fasulo)
Bonide Horticultural & Dormant Spray Oil label, EPA Reg. 4-80 (2024)
UC IPM Bee Precaution Pesticide Ratings (accessed 2026)
Page status
Drafted from the sources below, then checked claim by claim against those sources on 23 September 2026.
Suggest a correction →