Did you discover pale-looking trails on your spinach leaves? The leafminer is the likely culprit of this damage, leaving unsightly marks on the plant leaf as it devours the leaf tissue. Discover how to treat leaf miners on your garden plants and keep them from returning.
The leaf miner is a common insect pest. It munches away on the leaves of various plants and lays eggs within the leaf surface. The eggs hatch, leafminer larvae emerge, and a new generation of leaf miners becomes an infestation.
Typically, leaf miner insects do not affect plant growth. Yet, sometimes, they infest edible leaf plants, like lettuce, spinach, and Swiss chard. Unfortunately, leafy greens with bug trails are unappealing in a salad.
Since we prefer to eat bright green, unblemished greens, we take pest control measures as soon as we notice leaf miner activity. Luckily, leaf miners are relatively easy to eliminate and manage with a range of commercial and natural pesticides and preventative measures.
Treating and Controlling Leaf Miners
The leaf miner is a nuisance. It eats different plant and tree leaves and quickly infests the yard. Find out how to treat your fruit and vegetable patch and keep this insect pest from ruining your citrus tree or edible greens.
What Are Leaf Miners?
There are many pests in the insect world, and leaf miners are just one of them. But what are they, and why are they a cause for concern? Learn how to identify a leaf miner and its habits and life cycle.
Leaf miners are a type of insect that ranges in size and form and includes the citrus leafminer, boxwood leafminer, and spinach leafminer. They resemble tiny house flies and are black to gray with transparent wings and yellow stripes. The eggs appear as raised spots on the leaves, and the larvae look like tiny maggots.
These insects get their name because they eat or mine plant cells and material between the leaf’s top and bottom surfaces, leaving a translucent trail of damage. The pupae overwinter in the soil and come out as adults in the spring.
Leaf miners then find a suitable leaf for egg-laying, and the leaf miner larvae eat the leaf inside for two to three weeks before dropping back into the soil to become pupae.
Several generations of leaf miners can occur during one growing season when the conditions are warm. This reproductive behavior makes it challenging to stop an infestation after it starts.
How to Tell if You Have a Leaf Miner Infestation
Sometimes, it’s hard to know if your plants suffer from something as minor as the changing weather or more destructive, like insect pests. Knowing what to look for in an infestation is the first step in leaf miner treatment. Learn common signs of adult leaf miners, their eggs, and larvae.
Light-colored trail scars on plant leaves are one of the most apparent signs of leaf miners. Tiny bumps that contain eggs on the undersides of leaves are another indication of an infestation. One final way to determine if you have a leaf miner problem is the appearance of blotches on leaves, making them look variegated.
Timing for Leaf Miner Treatment
Treating leaf miners is relatively simple. Yet, there is a right and wrong time for leaf miner treatment. For instance, performing pest control when they are least active or dormant is less effective than when they are adults.
Treating Leaf Miners
The best time to stop a leaf miner infestation is spring while the insects are in the larvae stage. To determine if the timing is right, place a few suspected leaves from your plants in a plastic bag in early spring. Check the bag daily, and as soon as you see tiny flies, begin spraying your plants daily for a week.
Treating Leaf Miners With Pesticides
A commercial pesticide is the most effective leaf miner treatment, but it’s vital to use the correct product for the job. For example, some treatments kill beneficial insects and leaf miners, creating an imbalance in the garden.
Leaf Miner Pesticides
Not all pesticides effectively eliminate the spinach, boxwood, or citrus leaf miner, so checking the label for application and use is vital. Sevin, malathion, and lindane are a few examples of insecticides that treat these pests. However, ensure they are safe for use on fruits and vegetables beforehand.
Monterey Garden insect spray contains spinosad, a natural substance toxic to insects and safe for food crops. Whichever brand you decide to use, follow the directions and apply it as recommended. Generally, you mix the insecticide with water and spray it over the infested leaf, preferably in early spring.
How to Treat Leaf Miners Naturally
There are other options if you don’t want to spray your edible plants with an insecticide. Hand-picking is an excellent alternative to chemical bug applications. It’s better for the environment and eliminates leaf miners without harming good insects.
Natural Leaf Miner Control
The simplest way to treat your plants and remove leaf miners is to hand-pick the infested leaves. The leaf miner larva is already doing damage, but it’s trapped within the affected leaf. Since they can’t do any more harm until they pupate, plucking the leaves and disposing of them solves the problem.
Do not put the leaves in the compost after removing them. The heat of the compost pile may not be strong enough to kill the larvae, and you’ll reinfect your plants.
Use Diatomaceous Earth to Eliminate Leaf Miners
Diatomaceous earth is great for treating leaf miners and other harmful insects. It’s a naturally occurring powder that is safe for leaf and soil application, and it causes dehydration and death to insect pests.
DE Leaf Miner Treatment
Food-grade diatomaceous earth is an organic treatment for leaf miners and other insects. Most home improvement centers carry this product in the garden section. It comes in powder form in large bags and kills bugs after they crawl across it.
On a day without wind or rain, spread the diatomaceous earth over the plant leaves and the soil around the plant’s base. The powder kills insects on the plant and those traveling over the ground within 24 hours.
Beneficial Insects That Eliminate Leaf Miners
There are just as many good bugs in nature as bad ones, and some keep harmful insects in check. Learn how to control leaf miners and reduce their population by introducing beneficial insects.
Introducing predatory insects to the yard is an excellent way of letting nature do the job of pest management for you. For example, the parasitic wasp (Diglyphus isaea) parasitizes leaf miner larvae, killing them before they become adults. This beneficial insect is available online; all you have to do is open the container and walk through the infested area to set the wasps free.
Soldier bugs and ants consume large numbers of leaf miners. The nematode is helpful for introduction into the soil. Certain nematodes kill leaf miner pupae while they’re in the dirt, keeping them from emerging and laying more eggs.
Tips for Preventing Leaf Miners
It’s always better to stop a problem before it starts, and insect control is no different. Find out how to keep leaf miners from invading your trees and plants by taking pest prevention steps.
Keep an eye on your plants in the early spring and promptly remove leaves you suspect have leaf miner damage. Rotate plants each year, especially if you notice insect damage on your plants the previous year. Leaf miners overwinter in the soil, and moving the garden to a new location makes it challenging for them to find their favorite greens.
Companioning planting is a great way to mix plants in groups instead of growing large patches of plants leaf miners love. For example, leaf miners hate rosemary, lavender, fennel, dill, and marigolds. Planting leafy greens in a mixture of these plants keeps the pests at bay.
Install row covers over your plants to keep adult insects from laying eggs. Remember that these covers are ineffective if you’re planting in the same infested area as last year. This is because the pests overwinter in the ground and emerge beneath them.
Avoid treating plants with a broad-spectrum pesticide that kills both the leaf miner and beneficial insects. Instead, keep the veggie patch weed-free and clean up the garden in the fall to reduce the number of leaf miners next spring.
While leaf miners aren’t as destructive as other pests, leaf miner damage leaves plants blemished. They munch on everything from leafy greens to citrus and boxwood trees, laying eggs and causing infestations. Taking vegetable insect control steps is essential to help your plants flourish.
We hope that learning how to treat leaf miners keeps your plants healthy and delicious, and we’d love it if you’d share our tips for treating leaf miners with the gardeners in your life on Pinterest and Facebook.