. Handbook of nature-study for teachers and parents, based on the Cornell nature-study leaflets. Nature study. Insect Study 409 Supposing the fly which wintered behind the window ctirtain in your home last winter, flew out to the stables about May ist and laid 120 eggs in the sweepings from the horse stable, all of which hatched and matured. Supposing one-half of these were mother flies and each of them, in turn, laid 120 eggs, and so on for five generations, all eggs laid developing into flies, and one-half of the flies of each generation being mother flies. How many flies would the fly that
. Handbook of nature-study for teachers and parents, based on the Cornell nature-study leaflets. Nature study. Insect Study 409 Supposing the fly which wintered behind the window ctirtain in your home last winter, flew out to the stables about May ist and laid 120 eggs in the sweepings from the horse stable, all of which hatched and matured. Supposing one-half of these were mother flies and each of them, in turn, laid 120 eggs, and so on for five generations, all eggs laid developing into flies, and one-half of the flies of each generation being mother flies. How many flies would the fly that wintered behind your crurtaiti have pro- duced by September? 12. Pour some gelatin imsweetened, on a clean plate. Let a house- fly walk arotmd on the gelatin as soon as it is cool; cover the plate to keep out the dust and leave it for two or three days. Examine it then and see if you can tell where the fly walked. What did it leave in its tracks? 13. Write an essay on the house-fly, its dangers and how to combat it, basing the essay on Bulletins of the U. S. Department of Agriculture. THE COLORADO POTATO-BEETLE Teacher's Story HE potato-beetle is not a very attractive insect, but it has many interesting peculiarities. No other common insect so clearly illustrates the advantage of warning colors. If we take a beetle in the hand, it at first promptly falls upon its back, folds its legs, and antennae down close to its body, and "plays possum" in a very canny manner. But if we squeeze it a little, immediately an orange-red liquid is ejected on the hand, and a very ill-smelling liquid it is. If we press lightly, only a little of the secretion is thrown off; but if we squeeze harder it flows copiously. Thus a bird trying to swallow one of these beetles, would surely get a large dose. The liquid is very distasteful to birds, and it is indeed a stupid bird that does not soon learn to let severely alone orange and yellow beetles, striped with black. The source of this offensiv
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