When leaf miners attack your plants, they cause a dramatically dreadful appearance. Even worse, they can cause very serious damage.

This is why it’s very important to take steps immediately to get them under control the moment you begin to see symptoms of leaf miner predation.

In this article, we will discuss the symptoms to look for and share information on how to rid your plants of leaf miners. Read on to learn more.

Leaf Miner Damage & What Are They?

There are a number of different types of leaf miners, but the damage they do to plants is fairly uniform.

Adult leaf miners look like small black flies, but it is not these flies that do to your plants directly. What does damage to your plants is the larva that these flies leave behind.

These larva live in the mid-tissue layers of a plants’ leaves. They are called miners because they mine the nutrients out of the leaves and create paths of emptiness in their wake.

If you do not get leaf miners under control, they will quickly skeletonize your plant leaves.

When you see their damage, swift action is imperative because once they have infested one crop, they will hang on infest crop after crop until they are reined in.

When these larva begin boring their way through the leaves of your plants, they will leave yellow, curvy lines in their wake. The insects may also leave unsightly blotches and spots on your plants’ leaves.

How to identify leaf miners

During their life cycle, leaf miners go through several stages we need to be aware of if we are to identify them correctly:


Be it for eating or for laying eggs, female insects pierce the upper surface of the leaves making a tiny oval-shaped hole that is yet visible to the human eye. As a matter of fact, it's to these punctures that you have to pay attention for they'll be the first signs revealing the presence of leaf miners in your cannabis plants. The eggs (from tens to hundreds, depending on the conditions) are inserted into the leave tissue, making them even more difficult to come across. Besides, they're about 0.25 mm long, meaning even the most skillful grower will struggle to spot them at first sight.


It's in this stage that leafminers wreak havoc. The eggs hatch and the little larvae start to eat up the leaves' contents, tunneling them. The good news is that these tunnels can easily be identified. They are like twisty translucent paths with brownish edges. Larval worms are mostly white and yellow, although they could be greenish too. About 3-5 mm long, they can be detected with ease by holding up a leaf to the light. These larvae use the stems to move around the plant but never come out.


Plentifully-fed fully-grown larvae break the leaf using their mouth hooks and fall to the substrate, where they bury themselves about an inch to give way to the pupa. There, or on the surface or the undersides of the leaves, the metamorphosis takes place. When larvae move to the pupal phase, they turn into slightly rounded and segmented brownish barrels of 2-5 mm.


Leaf miners emerge from the pupa like small winged 2 mm insects. Going from black to grey, they could show some yellow spots in various parts of their bodies. Their wings are small and translucent. The average lifespan of an individual is about 10-15 days and they spend the day mating, feeding, and laying.

How can a leaf miner invasion affect our cannabis plants

The temperature and moisture levels are key to the development of leaf miners. Very humid and hot environments with temperatures exceeding 77°F are more likely to receive the visit of these damaging insects. At 60°F or below, females stop laying eggs.

If leaf miners have already infested your cannabis plants, the small tunnels will hamper their development for they take up part of the tissue plants need to perform photosynthesis. As a result, leaves become totally or partially dry and the yield decreases.

Another important issue worth bearing in mind is that the holes that leaf miners leave when laying the eggs or coming out could serve as entry points for multiple pathogens which would further damage the plant.

How to Prevent Leaf Miners

Stopping leaf miners from feeding on your plants in the first place will save you a lot of time and effort. The treatment measures above certainly work, but preventing an attack will allow you to keep growing in peace and avoid the hassle and worry. Use the methods mentioned below to prevent leaf miners from ever tasting the insides of your cannabis plants.

Clean Grow Space

Crops may tolerate less than ideal conditions for a time, but eventually the stress will weaken them and they can succumb to pests. Planting in the right place is an easy step toward preventing garden pests.

Obviously, we cannot discuss the benefits of using a marijuana grow tent without discussing their ability to decrease the possibility of insect infestations. Aphids, flies and spider mites are just a few of the most typical insects that infest indoor gardens.

Marijuana grow tents safeguard plants from bugs such as these with their enclosed design. However, there’s always a chance that some can contaminate your garden, though unclean gardening practices, bringing in materials or plants from another location, or having pets running around your gardening area.

These can all be kept to a minimum or eliminated if proper precautions are taken when gardening and working with your marijuana plants.

Row Covers

Mesh row covers provide a solid line of defence against leaf miner adults. These protective layers allow adequate light and airflow while still being small enough to block flies and moths from gaining entry to lay eggs. Row covers work well both indoors and outdoors. Just make sure to frequently check for any openings along the bottom of the cover where leaf miner species can sneak in, especially after strong winds.

Regular Observation

Regularly strolling through your grow room or garden to check for symptoms of invasions and disease will help you contain problems before they become major outbreaks. Go and check on your plants once each day. Look for changes in fan leaves and keep an eye out for those signature white trails.

If you find even the slightest sign of leaf miners, remove the affected leaves from the grow space. You might just prevent significant damage through an almost effortless act.


It is critical to ventilate the grow space adequately. This piece of advice is so important that it should be included under cannabis growing rules instead of cannabis growing tips. Adequate airflow can prevent mold from growing on the buds. It can also prevent nutrient burn, because when where you are growing gets very hot, the plants “drink” more water to combat the heat.

As they take more water, they absorb nutrients as well, increasing the risk for nutrient burn. Spider mites, fungus, gnats, and other pests also thrive in places with insufficient airflow. As you can see, many of the problems that cannabis growers face can be sidestepped if the grow tent ventilation are adequate for proper airflow.

Prevent First, Treat Later

The key to protecting your cannabis crop from leaf miners lies in prevention. If you’ve experienced an attack before—or you’ve received accounts from local growers—erect row covers just in case.

If you happen to be halfway through the growing season and have just discovered those dreaded white trials, try the treatment methods above as soon as possible. You’ll be back on track in no time at all!

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.

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.


When your garden is being visibly consumed by ravenous pests it can be very tempting to mount an aggressive and poisonous offense against them. While spraying can be effective in the short term, it may end up causing more problems with the passage of time.

Using a marijuana grow tent kit, you can have complete control over your gardening and growing procedure through it. This is a grow tent necessary for having safe gardening.

Protecting your garden from potentially hazardous chemicals also protects you, your family and the environment. Understand that when you are using natural, organic alternatives you must be very diligent, patient and persistent. With natural solutions, you should strive to attain a harmonious balance in your garden. This natural balance will help protect your garden against leaf miners and many other forms of pest.