Handbook of Nature-Study · Lesson LXXIX · Topic 10: Insects that live in leaves
79. The gall-dwellers
Goal: Your child can find several kinds of galls, open one to see who lives inside, and explain how the gall is both house and food.
You'll need
- Galls: oak apples, goldenrod ball and spindle galls, willow cone-galls, witch-hazel galls
- A small knife (for the adult)
- A jar with a cloth cover held by a rubber band
- A hand lens (magnifying glass)
- A nature notebook and a pencil (colored pencils if you have them)
What's in the book
Comstock's story of galls, which opens with Aladdin's palace: the oak apple and its tiny wasp, the willow cone-gall, the goldenrod ball gall made by a fly and the spindle gall made by a moth caterpillar that cuts its own door, and witch-hazel galls. Then Lesson LXXIX's leading thought, method and nine questions, and a poem by a gall-dweller. The scan's left margin is cut off at the start of this lesson, so the leading thought and the start of the method are only partly readable.
The lesson, step by step
When and where
Fall and winter are easiest: round balls on dead goldenrod stems stand out in snowy fields, and oak apples lie under oak trees. In summer, look on oak and witch-hazel leaves and at willow twig tips. In grass and woods, wear long pants tucked into socks, and check everyone for ticks when you get home.
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.
An adult does any cutting, on a board, cutting away from the hands.
The big idea
The scan cuts off the edge of Comstock's leading thought, so here it is in plain words: a gall is a growth on a plant that protects a little insect living inside, and each kind of insect makes its own kind of gall on its own kind of plant, though no one fully understands how.
Collect and compare
On what plant or tree did this gall grow? Were there many like it? Did they grow upon the root, stem, leaf, flower, or fruit?
What is the shape of the little house? What is its color? Its size? Is it smooth or wrinkled on the outside? Is it covered with fuzz or with spines?
Open one
Have the adult cut one gall of each kind in half. Keep the rest whole.
Open the gall; is there an insect within it? If so, where is it and how does it look? What is the appearance of the inside of the gall?
Is there a cell for the insect at the very center of the gall, or are there many such cells?
Has the house an open door?
House and pantry
Of what use are these houses to their little inmates? How do they protect them from enemies? How do they furnish them with food?
Comstock compares the oak-apple grub to a boy living in the middle of a giant sponge cake. Ask your child to explain why.
Wait and see
The readable part of Comstock's method says:
Place each kind of gall in a tumbler or jar covered with cheese-cloth and place where they may be under observation for perhaps several months; note what sort of winged insect comes from each.
Keep the jar somewhere cool, and let anything that comes out go outdoors.
Nature notebook
Draw each kind of gall whole and cut in half, with the plant's name. Copy a line or two of the gall-dweller's poem from the book page, such as "A house grown by magic".
Afterwards
Comstock's last question: "How many kinds of galls can you find upon oaks? Upon goldenrod? Upon witch-hazel? Upon willow?" Keep a running list this season.