Handbook of Nature-Study · Lesson LXXV · Topic 9: Butterflies and moths
75. The hummingbird, or sphinx, moths
Goal: Your child can recognize a sphinx caterpillar by its horn, and describe the swift sphinx moth that hovers at flowers at dusk.
You'll need
- Tomato or potato plants (for hornworms), or Virginia creeper
- Petunias, honeysuckle, phlox or four o'clocks to watch at dusk
- A flashlight
- 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 the sphinx moths: their whirring flight at twilight, the caterpillar with "a horn on the wrong end of the body" that rears up when disturbed, the pupa with its "jug handle" tongue case, and caterpillars covered with the cocoons of tiny parasites. Then Lesson LXXV with questions on the caterpillar and the moth. Some of the questions are printed in two columns and the scan's text is jumbled there.
The lesson, step by step
When and where
Late summer and September. The big green caterpillars (hornworms) feed on tomato and potato plants; others feed on Virginia creeper. The moths hover at petunias and other long, tube-shaped flowers at dusk, and some kinds visit flowers by day.
Safety first
The horn looks fierce but cannot sting or hurt anyone. Handle the caterpillar gently and put it back on its plant. Don't eat tomato or potato leaves. Wash hands with soap and water afterward.
Comstock suggests catching moths with a net. Watching at the flowers is enough; if you do net one, look for a minute and let it go.
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 sphinx caterpillars have a slender horn or eye-spot on the last segment of the body. When disturbed or when resting they rear the front part of the body in a threatening attitude. They spin no cocoons but change to pupæ in the ground. The adults are called humming-bird moths, because of their swift and purring flight. Many flowers depend upon the sphinx moths for carrying their pollen.
Find a hornworm
Look for chewed leaves and dark droppings on the ground under them, then look along the stems.
On what plant is it feeding? What is its general color? Is it striped? What colors in the stripes? Are they oblique or lengthwise stripes?
Note the horn on the end of the caterpillar. What color is it?
Touch it gently near the head and see whether it rears up like the Egyptian Sphinx.
Little white cocoons
Have you ever found the sphinx caterpillar covered with whitish, oval objects? What are these?
They are the cocoons of tiny wasps whose young grew inside the caterpillar. Leave such a caterpillar in the garden: the wasps that come out will help keep hornworms down.
The moth at dusk
Sit near the flowers as it gets dark, with the flashlight off until you need it.
Where did you find this moth? How did its swift moving wings sound?
From what flowers do the sphinx moths get nectar? How does the moth support itself when probing for nectar?
Many people think they have seen a hummingbird at night; ask your child why.
Put it into words
Ask your child to tell you the whole life story: caterpillar with a horn, pupa in the ground, moth at the flowers. Then read the leading thought aloud.
Nature notebook
Draw the hornworm with its slanted stripes and tail horn, and the moth hovering at a flower with its long tongue reaching in. Date both.
Tip
Comstock warns that "It is useless for the amateur to try to rear the adults from the pupæ in breeding cages." Watch the caterpillars on the plant and the moths at the flowers instead.