Leafminer – Have You Seen Their Tracks In Leaves?


Leafminer tracks in Aspen leaves. Photo via Flickr.

A leafminer can be found in the leaves of plants throughout the Rocky Mountains and North America.  Here is a quick overview on what a leafminer is.

Have you ever looked at a leaf and seen what looks like a track that goes throughout the green part of the leaf?  That is a leafminer.  Well, actually that is just the trail where it has been.  While the actual insect may be hard to see, you can see evidence of them quite easily.  This makes them a great example to talk about to explain the lifecycle of insects.


Photo via Flickr.

What Is A Leafminer?

A leafminer is the larval stage of many different insects including beetles, black flies, and moths.  They hatch from eggs that are on the leaves and tunnel into the leaf.  Then they live inside of leaves, between the upper and lower part of the leaf, and eat the inside part of the leaves.  As they do this they leave a trail that shows where they have been.

The leaf protects them from many predators so that they can eat and grow for up to three weeks before they change into an adult.

Insect Lifecycle

I want to talk about the insect lifecycle for a second to make sure the above explanation is clear.  As I stated the leafminer is the larval stage of several different insects.  The larvae is one stage in an insects life.

All insects undergo metamorphosis, which basically means that they change their form during their lifetime.

Most insects are born from an egg and become a larvae.  A larvae is like a child or immature insect that can’t reproduce.  Then at some point that larvae will change it’s form into the adult insect.  It can do this change in a couple of different ways, but the point I want to make here is just that the insect starts as a larva before it changes into its adult form.


Look at the tracks in this leaf. Photo via Flickr.

Do Leafminers Damage Plants?

Not usually.  They don’t generally kill or seriously injure a plant, but they do cause a poor appearance in the plant.  However, for younger plants they may cause enough damage that the plant dies.

What Kind Of Trees Does a Leafminer Live In?

A leafminer can live in the leaves of many different plants and trees.  Some of the trees include cottonwood, birch, aspen, and ponderosa pines.