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Leaf Miners: What Are They And How Do You Control Them?

Leaf miners are responsible for the silvery lines you see on your plant. They are common houseplant pests that feed on plant leaf tissue. They do this in the most peculiar ways by eating the plant from within.

At first, the leaf miner damage on plant leaves might not seem severe. But if left untreated, it can lead to a complete disposal of the plant. This is why a leaf miner treatment and control plan is needed. But first what are leaf miners?

What is a Leaf miner?

Leaf Miners:

Leaf miners are often tiny larvae of flies, sawflies, beetles, and moths. They live in the leaf tissue of plants. They can be hard to describe as they come from a variety of pests and insects. The leaf miner acts as a leaf worm that feeds on the chlorophyll located in the inner leaf tissue. 

This often leads to a long visible line on the plant’s leaf that is unattractive to look at. In addition to that, they also leave behind frass or feces as they bore into the plant.  It is easier to identify the leaf miner bug by the damage it causes to the plant’s leaf.  

The Life Cycle Of Leaf Miners 

Leaf miners adopt a sexual mode of reproduction. Adult leaf borers mate with the female miners, who in turn produce eggs. These eggs are deposited at the base of young plant leaves. 

Over time, as the climate gets warmer, the leaf miner eggs hatch into leaf miner larvae. These tiny bugs possess a ferocious appetite that causes them to bore into the plants. They keep feeding and defecating within the plant till they fall off the leaf into another. 

It is possible for a leaf miner bug to spend its whole life cycle within a plant leaf tissue. But in most cases, they fall into the soil and become pupas and then adult insects.

For an average leaf miner, it should take a month before it becomes a pupa. This depends on the exact species though. 

Leaf Miner Damages On Plant 

Because leaf miners feed on chlorophyll, they can limit the plant’s ability to create food. In cases of a bad infestation, this can lead to stunted growth for the entire plant. Aside from the massive energy depletion, leaf miners are almost harmless to plants. 

For gardeners of edible and ornamental plants, the leaf miner damage can be very bad. This is because edible and ornamental plants with such damage are unattractive. This could lead to a reduced value of the plant. 

How To Treat Leaf Miners

Leaf miners can be difficult to control. This is because they are quite small and are lodged inside the plant’s leaf tissue. But they can be controlled using a process. It is called the Integrated Pest Management method.

This process includes  three control methods which are the; 

  • Physical Control Method 
  • Biological Control Method
  • Organic / Chemical Control Method

Physical Leaf Miner Control

You can start by destroying or disposing of plants with a sign of infestation. Squish the plant tips to kill leaf miner eggs or larvae.

Take good care of your gardens by keeping them clean and getting rid of any plant debris. You can also till the ground to disrupt pupae that might be forming in the soil. 

Trap crops like radishes and columbine could be planted to monitor signs of leaf miners. These are decoy plants that can be used to attract leaf miners.

Biological Leaf Miner Control

The biological control method involves introducing leaf miner predators to the plant. Lacewings and Parasitoid Wasps are great insects you could use to kill leaf miners. 

You can also introduce beneficial nematodes to the garden. They feed on leaf miners and other pests like thrips and bagworms. 

Organic Leaf Miner Control

You can make use of some organic leaf miner insecticides or pesticides. Neem oil is a great leaf miner killer. This can also be used in the form of a leaf miner spray by mixing with water. 

Products containing pyrethrin can also be used in killing leaf miners. But they are inorganic and can cause harm to beneficial insects. 

Frequently Asked Questions

Are leaf miners harmful?

The leaf miner does pose some level of threat to plants. They can lead to stunted plant growth. 

What does a leaf miner look like?

Leaf miners are the tiny larvae of most insects like flies and beetles.  They can range in color from black to gray to orange. 

What is the best spray for leaf miners?

Insecticide sprays containing pyrethrin are great for leaf miners. 

Is there a homemade leaf miner spray?

Yes, you can make one with neem oil and water.  Mix the two in a bottle and spray on the affected plant. 

Should I remove leaves with leaf miners?

Yes, leaves affected by leaf miners should be pruned. This would prevent leaf miners from spreading.