Handbook of Nature-Study · Lesson CXV · Topic 18: Daddy-longlegs and spiders
115. The white crab-spider
Goal: Your child can find a crab-spider hiding in a flower and explain how its color helps it catch insects.
You'll need
- Flowers in bloom: white and yellow ones are best (daisies, goldenrod, trilliums in spring)
- 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 crab-spiders, which walk sidewise or backward and spin no webs, and of the white crab-spider, which takes on the color of the flower it hides in: greenish white in the white trillium, yellow in goldenrod. Then Lesson CXV's leading thought, method and four questions, with a photograph of crab-spiders on goldenrod.
The lesson, step by step
When and where
Late spring through fall, in the middle of flowers where insects come for nectar. Comstock mentions white trilliums in spring and goldenrod in late summer. Look for a flower with a bee or fly sitting oddly still: it may be a crab-spider's catch.
Look, don't pick
Comstock's method asks children to bring a spider to school in its flower. Look at it in the garden or field instead. Don't pick wildflowers like trilliums: they grow back very slowly and are protected in some states. Spider safety: never pick up a spider you don't know. Look with a hand lens from a few inches away, touch webs only with a grass stem or a pencil, and never reach into a dark corner, woodpile or shed where you can't see.
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 white crab spider has markings upon its body of the same color as the flower in which it rests and is thus enabled to hide in ambush out of the sight of its victims—the insects which come to the flower for nectar.
Find one
What is the shape of the body of the crab-spider? Which of the legs are the longest? Are these legs directed forward or backward?
Watch how it walks if it moves: sideways, like a crab.
Hidden colors
How is the body marked? What colors do you find upon it? Are the colors the same in the spiders found in the trilliums, as those in other flowers? Why is this? Do you think that the color of the spider keeps it from being seen?
Do the crab-spiders make webs? How do they trap their prey?
Then read the leading thought aloud.
Nature notebook
Draw the flower with the spider hidden in it, colored so it almost disappears, and its long front legs held open like arms. Then draw it again on a flower of a different color to show how it would stand out.
Tip
Comstock asks children to move a white spider into a yellow daffodil to see if it changes color. Scientists have since found that this kind of spider can change between white and yellow, but it takes days, not minutes.