Tuesday, October 13, 2009

Leaf Miner

Click on all photos for a larger views.

When I first thought of leaf miners I was really only looking at the tracks they make and not much about the insect itself. But after reading and doing more research I found out the term leaf miner is used to refer to any species of insect whose larva spends part or all of its life between the epidermal or outer layers of a leaf. It’s like a little cave inside the leaf that the caterpillar creates for itself to hide and feed. They can also be found in fruit, grass, aquatic plants and stems.

Usually I photograph things while I’m on my walk and then learn about them later. This time was just the opposite, after reading about leaf miners for a couple of weeks, I left work early last Friday and stopped by Shenandoah River on my way home. I was amazed that I was seeing so much miner activity and recognizing leaf damage and characteristics that would have gone unnoticed before. These photos were taken within a few yards of each other. I also collected some to photograph through my microscope at home, but you can easily see these things with the naked eye or a hand magnifier.

As they feed they mine tunnels of various patterns -- this is what first caught my attention. A leaf mine can be used to identify its creator by the size, pattern and location of the mine. I find the Serpentine leaf miners are the most interesting as they wind and feed along in snake-like pattern across the leaf, some gradually widening as the larva grows. The most common are the blotch leaf mines created when the larva turns around and around during feeding. The shape can be irregular or in a circle or oval. One subgroup is the tentiform which looks like a bulging blotch-type mine. Sometimes you can find a combo serpentine ending in a blotch. In Insect Life and Insect Natural History, S.W. Frost states, “They write their signatures in the leaves, a habit which greatly assists in determining the species.” I would love to find such an identification key.

Leaf mining is not restricted to one group of insects but is used by the larva of Lepidoptera (moths), Coleoptera (beetles), Hymenoptera (sawflies) and Diptera (flies). Leaf miners generally begin their life with when eggs are laid in or on a specific host plant. Most spend their entire larval stage within the leaf while some will cut their way out and finish their life cycle outside the leaf.

You can hold up a left to the sun and often see the larva inside. Look in the light brown area where all the chlorophyll has been eaten.

The larva is tiny and flattened as compared to a butterfly caterpillar. They don’t have legs and their chomper mouth parts are projected forward to make it easier to feed their way between the top and bottom layers of the leaf.

I watched this one through my microscope as it was feeding. It was swaying side to side as it ate, just under the outer layer of the leaf.

The beetle leaf miner eggs are generally laid on the surface of the leaf and often covered with a shiny black coat. When they hatch the baby larvae bore into the leaf.

You can see the hole where this larva began its journey.

Most of the time the beetle leaf miners pupate within the mine, in the circular or oval cocoon, then they cut a small round disc from the leaf and fall to the ground to later emerge.

Sawfly leaf miners are almost always the blotch types and the eggs are laid into the leaf tissue.

The black doted stuff is fecal material.

The Lepidoptera (moth) leaf miners are the largest group and use a large combination of strategies for their mines including tentiform.

Leaf miners are very interesting any can be found most forested areas. I encourage you to go outside and look for some. You will be amazed at the variety of squiggly lines you can find.

Learn more one other ABC Wednesday blogs.


Squirrel said...


Trillium said...

Everything you ever wanted to know about leaf miners but didn't know you wanted to know so didn't ask!
Thanks for illuminating us. Fantastic photos!

photowannabe said...

Totally fascinating. I again learn something new from ABC Wednesday.
Magnificient pictures.

Paula Scott said...

WOW! What a great post and lesson! I love it! How did you get the microscope shots?
Fabulous, fabulous, fabulous!

Nukke said...

Good Grief ! That was interesting :)

RuneE said...

I must admit that I have never heard of leaf miners, but you have told the story so well with such fine illustrations, that I can only say Thank you!

James said...

What a great post. You really presented it well.

Babooshka said...

Now that is what I call an eductational post with some beautiful photography.

Carolyn Ford said...

Now I want to go out and hunt for "leaf miner" as well! Fascinating...and, impressive photography on this subject!

Tumblewords: said...

Spectacular photographs and narrative! Thank you!

~Cheryl said...

It's good to know I didn't know I didn't know all this. :) Fascinating! Now I have something else to ponder.

Rose said...

Fascinating info! I have often seen these kinds of markings on leaves; now I know what has created them. Thanks for sharing such interesting information, Squirrel.

Q said...

Wonderful M!
Thank you.
I want a microscope now.
Leaf Miners are very cool.

Joy said...

What a wonderfully informative post and some great photographs. It made me want to rush out to the nearest wood.

Roger Owen Green said...

Heavy duty zoology lesson with great photos. I knew almost none of this.

SquirrelQueen said...

That was fascinating, I really enjoy learning things like this. When I go out I also photograph new things for later study.
Great post Squirrel, I will be checking the leaves a little closer in the future.

Jay said...

Excellent post! I love studying leaf miners, and other insects, too. You got some great pictures - and I'm envious of you managing to watch a leaf miner eating under the microscope!

Jackie Callahan said...

Fascinating!! I was intriqued with your microscope photography, and your comments are so informative. Thank you!

Greenfingers said...

Absolutely fascinating set of photographs. I noticed an interesting mine on honeysuckle a couple of days ago but didn't have time to photograph it.... now you've prompted me to go back and take another look. Thanks.