Leaf Miners: How to Prevent and Get Rid of These Pests from Your Garden (2024)

So you’ve spotted some maze-like squiggly lines in your precious spinach leaves. Or maybe your crops are covered in annoying flies. Bad news: you could have an infestation of leaf miners.

Leaf miner infestations can happen in greenhouses, veggie gardens, and ornamental areas around your property. On top of that, they can show up in almost any region of the U.S. In other words – no one is safe.

The damage caused by leaf miners isn’t just unsightly, it can stunt or kill plants, so you need to understand how to treat these pests. Ready to learn how? Keep reading!

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What Are Leaf miners?

The term leaf miners is a catch-all that describes the larvae of three insect species: Lepidoptera, Diptera, and Hymenoptera. These larvae live inside plant leaves, feeding and growing until they reach maturity.

Basically, leaf miners are the larval – or maggot – stage of several insect families.

The first thing you might notice is distinct, discolored lines on foliage since these pests live inside leaves. That pattern of lines is a feeding tunnel created by the leaf miners as they chew through plants.

If you pay close attention to the patterns, you can identify the specific leaf miner variety that’s attacking your plants. You can also narrow down the leaf miner type by watching which plants are targeted.

Identification of Leaf miners

Host plants for leaf miners can include beans, blackberries, tomatoes, cucumbers, potatoes, lettuce, cabbage, peppers, citrus trees, aspens trees, shrubs, and a variety of ornamental flowers. As you can tell, they don’t pick one particular type of plant, which makes it harder to track these insects.

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The larvae look like worm-like maggots that can be pale yellow, dark brown, or light green.

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Adults measure 1/10 inch long and are typically black or grey flies with yellow stripes and transparent wings. They look similar to small house flies. They lay their eggs on the underside of leaves.

There are two common types of leaf miners, though keep in mind that there are several other varities out there:

Spinach Leaf miners

This species is a type of blotch leaf miner that creates irregular round-shaped mines. The mines are long and narrow at first, then become an irregular shaped patch.

There are a few ways to pinpoint spinach leaf miner larvae:

  • They don’t have legs or head.
  • The larvae are whitish and look like little carrots.
  • They create tunnels between the two leaf surfaces.
  • Once matured, the adult flies are hairy, measure ¼ inch long, and are between grey and brown.

Vegetable Leaf miners

Vegetable leaf miners feed on different plants than spinach leaf miners. This variety prefers beans, eggplants, squash, tomatoes, cucumbers, peas, and other edible plants.

Aside from looking at the plants they infect, here are some different ways to identify this species.

  • The larvae look like snakes that leave behind winding mines.
  • The larvae don’t have legs or a head and are yellow-green with a cylindrical shape.
  • This species is smaller than spinach leaf miners, only measuring around 1/15 inch in length. The adult flies are yellow and black.

The Life Cycle of Leaf miners

Understanding the lifecycle of leaf miners is essential to controlling them. It all starts when mature larvae overwinter in the soil under the plants. Then, as the spring temperatures warm up the ground, the larvae mature to their pupal stage. By late April, they’re young adults.

At that point. they’re ready to start laying eggs in your garden. Mated females use a needle-like ovipositor to lay up to 250 eggs under the surface of the leaf epidermis. It can be hard to spot the eggs under the surface; they appear as small raised bumps in the leaf.

The eggs hatch within ten days, and the larvae start to eat their way through the leaf tissue. This is when they leave behind the wavy lines that are visible on the surface.

Larvae take only 2-3 weeks to mature. When they’re ready to pupate, they ditch the leaf and drop to the soil, digging 1-2 inches into the ground. Then, 15 days later, they emerge as an adult fly.

You can have several generations of leaf miners in one single year, so it’s clear how quickly a leaf miner infestation can start.

How to Identify a Leaf miner Infestation

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It’s fairly easy to identify the damage caused by a leaf miner infestation because these pests feed on parts of the plants with tissue containing the lowest levels of cellulose and tannins.

They leave behind a distinct trail of maze-lime damage on plants. Typically, the damage is only cosmetic, and the plants continue to live a healthy life.

That’s not to say that leaf miners can’t kill a plant; they absolutely can! Unchecked damage can cause excessive leaf drop and other severe effects. The feeding tunnels created on the foliage can become pathways for diseases or fungal spores.

How to Prevent a Leaf Miner Infestation

As with any pest, prevention is the key to success. It’s easier to prevent an infestation rather than to stop one. Your best bet is to use multiple methods to avoid leaf miners from invading your garden.

Here are some suggestions.

Till Your Soil in the Fall

Leaf miners like to hide in the soil during winter and emerge as the temperatures warm. Till your garden after harvesting your crops in the fall to destroy the pupae and reduce the chance that adult flies will invade nearby plants.

Plant Trap Crops

Planting trap crops is a sneaky-yet-genius way to attract pests to crops you don’t mind sacrificing in order to save the ones you want. Leaf miners particularly enjoy lamb’s quarters, columbine, and velvetleaf. Plant these to prevent leaf miners from bothering plants that you want to keep whole and healthy.

Monitor Your Garden Closely

Monitor your garden closely and watch for any evidence that leaf miners are trying to make it their home. Catching issues early lets you take care of them faster and with less effort.

Keep Your Plants Healthy

If you have healthy plants, leaf miners won’t harm them as much. Use organic fertilizers and adequate watering techniques to ensure your garden is as healthy as possible. Add compost and other soil amendments to create a solid foundation for your plants.

Try Floating Row Covers

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Floating row covers can help stop the adult flies from laying their eggs on the leaves. Floating covers are inexpensive and easy to install over your garden beds.

Hang Sticky Traps

One simple trick that you can try is hanging sticky traps in your garden. The traps attract and trap the adult pests before they can lay their eggs.

How to Stop a Leaf Miner Infestation

So your prevention methods failed, or you never had the chance to stop leaf miners from invading. Now you have leaf miners making a meal out of the foliage in your garden.

What can you do to stop leaf miners in your garden beds?

Manually Remove Eggs

If you’re lucky enough to spot the eggs, manually remove them from your garden. The more eggs that you remove, the fewer pests you’ll have to deal with when they hatch.

Introduce Diglyphus Isaea

Diglyphus isaea is a beneficial wasp that parasitizes leaf miner larvae. It kills them before they can mature. D. isaea is the natural enemy of leaf miners, and they’ll make a meal of these pests in your garden.

To reap all of the benefits of this wasp, you need to release them early in the season before the leaf miner population reaches large numbers.

Be aware that if you spray pesticides in your garden, it will kill these beneficial bugs.

Break Out the Spinosad Pesticide

Notice large numbers of leaf miners destroying your foliage? It’s time to take action, and only a few sprays work well against these pests.

I’ve found that Spinosad works well in the fight against leaf miner infestations. You can apply it to all plant surfaces. Once these pests ingest the pesticide, it stops them from feeding and they die in 24-48 hours. You need to apply it 2-3 times per growing season to keep the population at bay entirely.

Spray Neem Oil

I’m a huge fan of neem oil; I’ve used it effectively against many different pests in my garden beds.

Neem oil can be applied as a spray (either pre-diluted or concentrated) to stop the growth and development of pests. It acts as a repellent and has antifeedant properties.

You can use neem oil, which contains azadirachtin, to eradicate a population of leaf miners.

The reason I use neem oil is that it’s non-toxic to honey bees and other beneficial insects. You need these in your garden for proper pollination and using traditional pesticides can kill them as well.

Kicking a Leaf Miner Infestation

The key to getting rid of a leaf miner infestation is to prevent it before it starts, but gardening doesn’t always work that way. Instead, if you find yourself with leaf miners invading your garden, opt for natural methods such as introducing beneficial insects and use neem oil to eradicate them.

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Leaf Miners: How to Prevent and Get Rid of These Pests from Your Garden (2024)

FAQs

Leaf Miners: How to Prevent and Get Rid of These Pests from Your Garden? ›

Pick off and destroy badly infested leaves in small gardens. Use floating row covers to prevent fly stage from laying eggs on leaves. Use yellow sticky traps to catch egg laying adults. Cover soil under infested plants with plastic mulches to prevent larvae from reaching the ground and pupating.

How to prevent leaf miners? ›

Physical barriers: Placing physical barriers, such as row covers or netting, over the host plant can help prevent adult leaf miners from laying eggs on the leaves. Remove and destroy infested leaves: Removing and destroying infested leaves can help reduce the population of leaf miners and prevent further damage.

What is the best homemade solution for leaf miner pests? ›

Apply neem oil: Neem oil is a natural insecticide that can be effective against leaf miners. Mix one tablespoon of neem oil with one quart of water and spray it on your plants.

What plants do leaf miners hate? ›

Plant some of these plants in your garden as a tactic for how to get rid of leaf miners:
  • Fennel.
  • Marigolds.
  • Rosemary.
May 4, 2021

What is the best chemical control for leaf miners? ›

Chemical management of leafminer
CropPermit number or registrationChemicals
Leafy vegetables (except lettuce)PER81876v4Abamectin
Legume vegetablesPER81867v2 PER81876v4Cyromazine Abamectin
Lettuce (head and leafy)PER88640Spirotetramat (suppression only)
Lettuce – head lettuce onlyPER81867v2Cyromazine
28 more rows

How to get rid of leafrollers? ›

A properly timed foliar spray of Bacillus thuringiensis (Bt) or spinosad controls leafroller larvae. Bacillus thuringiensis kills only caterpillars (butterfly and moth larvae). A second application of Bt about 7 to 10 days after the first is recommended because of its short persistence.

How to get rid of leaf bugs? ›

The most effective insecticides against leaffooted bug are broad-spectrum, pyrethroid-based insecticides, such as permethrin.

How do you treat leaf miners on tomatoes? ›

Managing Outbreaks:

Leaves displaying the larval mines can be removed and destroyed. Pupae that have formed on the leaves can also be removed and destroyed. Parasitic wasps can be purchased and released around affected plants when they are grown in greenhouses.

Does neem oil prevent leaf miners? ›

Neem oil is made from a plant and helps to halt the life cycle of a leafminer.

What eats leaf miners? ›

Predatory bugs, soldier beetles and ants consume leaf miners in large numbers. Ants cause particularly high mortality, when aphid colonies can be found close to mined leaves. The frequently visit these colonies for honey dew and also open the mines near their way.

Is it safe to eat leaf miners? ›

A: There would be no harm in accidentally eating a leaf miner larva from your spinach leaves. It would never parasitize an animal, being able to complete its life cycle only on a small group of related plants, namely spinach, chard and beets.

What do you spray leaf miners with? ›

If you notice leafminer damage on foliage, thoroughly apply Spinosad (Monterey Garden Insect Spray) to all plant surfaces. Once ingested, spinosad stops larvae from feeding and they will die within 24-48 hours. Repeat applicatons 2-3 times throughout the growing season if damage persists.

How to get rid of leaf-eating worms? ›

BT (Bacillus thuringiensis) is an organic way of controlling leaf eating worms in the garden or ornamental landscape. It is applied as a foliar spray, which is consumed by the worms. Once the BT is consumed by the worms, it will kill them in 2-3 days.

How do you keep leaf miners away? ›

Plants can be protected by covering them with row covers. This will stop adult leaf miners from laying eggs by denying them access to the leaves. All leaves infested with larvae need to be removed and discarded away from the plants. Plants should be watered regularly to keep them vigorous and healthy.

What causes leaf miner infestation? ›

Leaf miner damage is caused by the larvae of some moths, flies, sawflies, or beetles. As mentioned above, the adults lay eggs on the underside of leaves. The leaf miner larvae eat the chlorophyll in the plant when they hatch from the eggs.

What are the natural enemies of leaf miners? ›

Natural enemies, especially Chrysocharis and Diglyphus spp. parasitic wasps, commonly control leafminers. Choose selective pesticides when managing other seedling pests to avoid disrupting leafminer biological control. Consider installing insectary plants to attract natural enemies of leafminers.

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