Cannabis Plants and Leaf Miners

As you inspect your healthy cannabis plants, you come across a myriad of lines scattered across the green leaves. Each passing day brings about more zig-zag lines that are beginning to impact the overall health of your cannabis plants.

Leaf miners are the seemingly invisible enemy that produce these miniature tunnels and are a common pest for many agricultural crops, especially cannabis. Leaf miners are a serious threat that you must understand to keep your marijuana plants pest-free.

Picture of Roy Stevens
Written By Roy Stevens
Marijuana Plant used in leaf miners guide

Table of Contents

What Are Leaf Miners?

Leaf miners are a generalized category of insects in the larval stage. Insects that are typically classified as leaf miners are moths, sawflies, flies, and even beetles. Leaf miners range between 3-5mm in length and look like tiny maggots or worms.

However, the most common type of leaf miner that you may come across is those from the Lepidoptera family, which includes moths. Since you know that it’s moths or flies causing these leaf issues, why are they called leaf miners?

The primary reason behind this name is because it’s precisely what they do — they “mine” through the leaf tissue in search of food.

When any of these insects are in their larval stage, they are susceptible to a number of predators. Instead of waiting to get picked off by a bird, the larvae of flies and moths burrow into the leaves for protection and sustenance.

As leaf miners consume plant matter, they leave behind a trail of destruction that’s reminiscent of a topographic map. Once satisfied, leaf miners stop feeding and wait to undergo metamorphosis. As the insect transforms into its pupal stage, it falls to the ground.

Are Leaf Miners Dangerous For Cannabis Plants?

At first, the few zig-zag lines may seem harmless. You may think that a handful of tunnels on a single leaf out of hundreds of leaves isn’t an issue. However, you may quickly realize that leaf miner problems can snowball out of control if left unabated.

The primary reason you need to keep leaf miners off of your cannabis leaves is that they decrease the amount of photosynthesis that occurs, which decreases the plants’ overall efficiency.

Although it will take a severe outbreak of leaf miners to destroy your cannabis crop, they will provide a serious eyesore and slow the growth of your cannabis plants.

How to Prevent Leaf Miners

Prevention is always better than reacting to a leaf miner outbreak. Let’s take a look at the best ways to prevent leaf miners from tunnelling through your cannabis crop.

Keep Your Cannabis Plants Healthy – The golden rule for preventing any serious outbreak is to promote health. In the case of leaf miners and cannabis plants, you must ensure your plants are strong and healthy. The best way to maintain healthy marijuana plants is by proper feeding, lighting, and watering.

If your cannabis plants are healthy, they can quickly overcome and resist leaf miner outbreaks. If you keep your plants healthy, they will have the power to protect themselves.

Inspect Your Cannabis Plants Often – An important method in preventing leaf miner outbreaks is by inspecting your plants often. By doing so, you can identify and isolate a potential leaf miner hot spot before it cascades into a severe problem.

Bring In The Beneficial Insects – All animals are predators and prey at the same time. In other words, there’s always something ready to eat you. For leaf miners, they are prey for a parasitic wasp that will not harm your cannabis plants. Instead, Diglyphus isaea will eat all of the leaf miners that it can get its hands on.

Apply Organic Pesticide – Another helpful tip in preventing leaf miners in your cannabis garden is to use a preventative organic pesticide. Neem oil is a great botanical pesticide that can deter leaf miners and other harmful pests.

Use Floating Row Covers – For Your Cannabis Plants
Floating row crops are helpful to keep mature flies and moths from depositing larvae into the leaves. You must understand that larvae don’t just magically appear in the leaves, but are instead strategically placed there by mature insects.

Remember, by keeping leaf miners at bay, your garden will thrive. There’s nothing like seeing your cannabis garden reach its potential by producing a bumper crop of flowers. By preventing leaf miners, you increase your chances of a record-breaking harvest.

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