Handbook of Nature-Study · Lesson LXXVII · Topic 10: Insects that live in leaves
77. Leaf-miners
Goal: Your child can find leaf mines, name the three kinds Comstock describes, and explain how a tiny insect lives between the top and bottom of a leaf.
You'll need
- Leaves with pale winding trails or blotches (columbine, nasturtium, lamb's quarters, dock, burdock, beet, spinach)
- A hand lens (magnifying glass)
- A sunny window
- A nature notebook and a pencil (colored pencils if you have them)
What's in the book
Comstock's story of leaf-miners, beginning with Lowell's line about a leaf being "some happy creature's palace": how a leaf has living cells between its upper and lower skins, and how tiny larvae eat their way between them. Then Lesson LXXVII's leading thought, method and ten questions.
The lesson, step by step
When and where
Summer into early fall. Comstock suggests the nasturtium leaf-miner "in early September", but any garden or weedy lot will have mined leaves: look for pale winding lines and brown blisters.
Safety first
Before you go, learn to recognize poison ivy ("leaves of three, let it be"), and poison oak or poison sumac where they grow. We never eat any wild berry, leaf or plant.
Don't nibble the leaves you are studying, even garden ones. Wash hands with soap and water afterward.
Keep the big idea in mind
Comstock's "leading thought" is the one idea the lesson is meant to lead to. Read it to yourself now, and save it to share at the end, after your child has looked and answered:
The serpent-like markings and the blister-like blotches which we often see on leaves are made by the larvæ of insects which complete their growth by feeding upon the inner living substance of the leaf.
Three kinds of mines
Read Comstock's sorting rule aloud:
There are three general types of mines: Those that are long, curving lines called serpentine mines; those that begin small and flare out, called trumpet mines; and those that are blister-like called blotch mines.
Sort your leaves into three piles.
Look through the leaf
Hold a mined leaf up to the window.
Hold the leaf up to the light, can you see the insect within the mine? What is it doing? Are there more than one insect in the mine?
Study a serpentine mine. Note that where the little insect began to eat, the mine is small. Why does it widen from this point?
A safe house
Why does an insect mine in a leaf? What does it find to eat? How is it protected from the birds or insects of prey while it is getting its growth?
Then read the leading thought aloud.
Nature notebook
Comstock's first question is the notebook task:
Sketch the leaf with the mine in it, showing the shape of the mine. What is the name of the plant on which the leaf grew?
Draw one of each kind of mine if you found them.
Afterwards
Comstock's question 10 says not to pick a leaf with a miner at work, but to cover it on the plant with a little bag of thin cloth. Tie a mesh produce bag over one mined leaf and check it every few days to see what comes out.