Citrus leafminer is a destructive pest during its larvae stage. It majorly causes foliage damage. As a result, stunting growth, exposing citrus to secondary plant diseases and low-quality fruit production can occur. Get information on how to identify them (pictures), and possible means by which you can treat, control and manage citrus leafminers.
The pest attacks all varieties of the citrus plant family namely: lemon, orange, lime and other citrus trees.
Also known as Phyllocnistis citrella, citrus leaf miners are native to Asia. These insects were found and reported in Western Australia in the 1940s. They have since spread to many regions of the Americas.
How to Treat, Stop or Prevent Leaf Miners on Citrus
Successful control of the pest means that you have to carefully scout your citrus trees regularly.
1) Protect the Young Citrus Trees
Young citrus trees in their first three years of growth are more vulnerable to leaf miner attacks. Protect your transplanted seedlings and citrus trees as soon as new shoots have formed. If you opt for imidacloprid, use it in the spring, once a year only. Do not spray imidacloprid when the citrus trees bloom, however.
You can also protect the seedlings by applying a horticultural oil in the spring. As you spray, make sure the oil covers the whole leaf. Re-apply after 1 – 2 weeks. However, when leaves start to turn dark green stop spraying.
2) Prevent or Disrupt Males from Mating
Attract the citrus leafminer males with baits of sexual pheromone. Pheromone is a strong chemical hormone that disrupts males’ ability to locate females. Once attracted, kill them using imidacloprid. Ask for a product called “SPLAT-CLM” which is available on commercial sale.
3) Establish A Natural Predator
The existence of certain species of parasitic wasps and spiders in your garden can help save your citrus trees. Two of the best species of parasitic wasps are the Ageniaspis citricola and Cirrospilus quadristriatus.
Sympiesis sp. and Zaommomentedon brevipetiolatus have been introduced or used in Australia. Reportedly, these natural enemies offer good control of the pest, especially in areas it has been introduced.
It is recommended that you be spraying insecticides to stop citrus leafminers early in the morning. This is to avoid accidental disruption of the natural predators.
4) Apply Soil Drench
According to the University of Georgia Extension, Admire Pro 4.6F, Admire 2F, Alias 4F, Alias 2F are the best controls for preventing leafminer larvae damage.
5) Apply Organic (Fertilizers) Compost
In one study research conducted by the US National Library of Medicine, between 2016 and 2017, applying certain compost manure can be quite an effective citrus leafminer control. According to this study:
Biofert applied at 0.5 kg/citrus tree reduced infestation up to 54.5% during the fall. Infestation also went down further after applying biofert in the summer
Subsequent application of vermicompost at 0.5 kg/citrus tree reduced the number of larvae per leaf. It was also found out that vermicompost greatly offered protection of the citrus tree against citrus canker disease.
6) Early Removal of Mined Leaves
If you have a backyard of a citrus orchard in your home garden, removing damaged leaves as early as you notice signs of leafminers is an easy and cheap fix. Identify the rolled, curled leaf margins and mined leaves as early as you notice the signs and cut them off. Additionally, prune late in the summer and autumn.

7) Prevent Moths From Laying Eggs
Stopping the females from laying new eggs is another way of controlling citrus leafminers. By doing so, it means that the life cycle of any subsequent generation is cut or interfered with.
Gardeners, as well as farmers, can use organic oils. You may opt for a certified horticultural oil available in garden centers.
To prepare yours at home, simply add 1 teaspoon of liquid detergent to 1 cup of ordinary vegetable oil. Mix with water such that the ratio of water:detergent+oil is 40:1. Spray on the upper leaf side more but don’t ignore the underside.
More importantly, apply oils when the air temperature is under 35°C (95°F). Otherwise:
- Apply well-stored oils free from exposure to sunlight
- Avoid oil application when soils are dry
- Avoid applying mineral oils for as long as the whole citrus fruit production period
8) Fertilize In The Winter
Fertilizer application in the winter means that your citrus trees will flush. The pest population during the winter season is also scarce. Nonetheless, avoid excess nitrogen fertilizer and irrigation, especially toward the end of the summer and autumn.
9) Re-apply Insecticides
Why is it important to reapply insecticides? By the time citrus leafminers reach the larvae stage, the residual effect of insecticides goes down. As a result, most registered insecticides deem less effective.
The best time to spray is the beginning of the summer flush (or when fresh shoots have formed). During the hot weather, re-apply after 7 days. When conditions are cooler, spray again after at least 10 days or at most after 2 weeks.
NOTE: Do not use broad-spectrum insecticides to kill adult citrus leafminers. These kinds of products disrupt the lives of natural control predators or larvae eaters.
For optimal treatment, it is important to know the stage of the life cycle of the citrus leafminer at the time you intend to apply insecticides. Killing these pests using registered insecticides needs to be super timely.
How to Identify Leafminers on Citrus (Signs)
Proper treatment means you first have to identify the insect correctly.
By Citrus Leafminer Damage (Larvae Stage)
Damage is most evident in young immature citrus leaves. The citrus leaf miner bores mines at the larvae stage only. These mines can be described as being squiggly (see picture). This is usually the first symptom of a citrus leafminer attack.
As they feed, they leave feces. At times the feces form a trail which is usually more visible in the mines as dark threads (see picture below). With increased infestation, the leaves look malformed.

After the larvae have grown, they stop mining. Instead, they move out of the mines to curl the citrus tree leaf edges. As a result, the leaf shape looks distorted. Inside the leaf curling, they hide to protect themselves while preparing for the pupa stage.

By Studying Citrus Leaf Miner Adults
Adult citrus leafminers are small moths. Their bodies are less than ¼ an inch long. They have narrow pairs of forewings and hindwings. The outer edges of these forewings have long hairs.
Each upper surface of the forewing has a dark spot toward the wingtip. The inner edges of each forewing have dark and irregular lines. While the inner regions of these forewings look silvery due to scales, the outer regions have silver, light yellow, and brown scales. The hindwings of citrus leaf miners are narrower than the forewings.

All adults are active early in the mornings and later evenings. They mostly spend their daytime under the leaves because they are less active.
Notably, the adults do not cause leaf damage. And can live up to 2 weeks.
By Identifying the Eggs
Female adult moths lay very tiny eggs. They are flat and oval. Laid eggs are translucent white. Due to green matter in leaves, the eggs appear light green when observed against the leaf blade.

More often, you can find these eggs under the leaves deposited nearer the middle leaf veins. Sometimes, the eggs are laid on top of the leaves. This happens in case of citrus leafminer infestation, or when the leaves are too moist (very humid air conditions).
By Understanding the Life Cycle
The citrus leafminer undergoes different growth changes. Understanding these stages is important for anyone doing citrus production. Like many insects of other families, the life cycle of the citrus leafminer comprises 4 stages.
Egg: Stage 1
The eggs are laid by females 1 week after mating. New tiny larvae emerge out of the eggs and start feeding.
Larvae: Stage 2
In about 14 – 21 days, the larvae grow or molt four times (instars) while in the leaf; feeding and mining. The first three (of the 4 instars) stages are spent feeding on sap. In the summer, the larvae can feed on sap for nearly 1 week. The fourth instars are the prepupa. It can be spotted being yellowish to brown.
Notably, the prepupa does not feed since this is the first point of emerging out of the mines. As noted earlier, this is the most destructive stage.
Pupa: Stage 3
Soon after the larvae emerge from the mines as prepupa. They then become pupa when they roll the citrus leaf by the leaf margins. This pupal stage can last from 1 – 3 weeks (7 – 22 days).
Adult: Stage 4
Finally, the pupa grows and turns into an adult. We have described the adult citrus leafminer above (how to identify citrus leafminer) in detail.
It takes only about 3 to 7 weeks for the complete cycle. This means the leafminers can invade your citrus trees a couple of times in a single season of production.
The Risks of Leaf Miner Infestation
If you do not stop and effectively control the leafminers, your citrus plants’ productivity is put at stake. Besides young foliage damage, citrus leafminers can affect health and hence growth. Below are the risks associated with citrus leafminers.
Secondary Plant Disease
The damage (leaf mines) easily exposes the trees to secondary disease-causing microorganisms such as the bacteria responsible for citrus canker disease

Physiological Problems & Other Pests
The leafminers interfere with various plant biological processes including photosynthesis, exchange of oxygen (respiration) and plant nutrition. The larva damage also exposes leaf cuticles to other tiny pests.
Sources And References
- Citrus leafminer. Department of Industries and Regional Development. https://www.agric.wa.gov.au/citrus/citrus-leafminer. Accessed online 28 Aug 2021
- Citrus Leafminer. ABC Gardening Australia. https://www.abc.net.au/gardening/factsheets/citrus-leafminer/9429694. Accessed 28 Aug. 2021
- Citrus leafminer. NSW Department of Primary Industries. https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0006/137634/citrus-leafminer.pdf. Accessed 28 Aug. 2021
- Arshad M, Ullah MI, Qureshi JA, Afzal M. Physiological Effects of Citrus Leafminer Phyllocnistis citrella (Lepidoptera: Gracillariidae) Larval Feeding on Photosynthetic and Gaseous Exchange Rates in Citrus. J Econ Entomol. 2018 Sep 26;111(5):2264-2271. doi: 10.1093/jee/toy150. PMID: 29878210.s
- INDIVIDUAL PROTECTIVE COVERS (IPCS) FOR YOUNG TREE PROTECTION FROM THE HLB VECTOR, THE ASIAN CITRUS PSYLLID. IFAS Extension. https://edis.ifas.ufl.edu/publication/HS1425. Accessed online 30 May 2023
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