A. Lady-beetle.
B. Burying-beetle.
C. Oil-beetle.

All were attention at once.

"Many years ago there lived away out in California a little, round, brownish, striped beetle, which crawled about and ate heartily of a plant called the sand-bur. One day one of the family happened to wander up to a nice, juicy potato plant. After eating its fill it probably looked up some of its brothers and sisters, and told them about these good plants growing in the fields. With one accord they left the sand-burs and began to eat the potato plant. Farther and farther they wandered, until thousands of them reached the eastern part of our country, eating the potato plants wherever they found them on the way. Now, these beetles are to be seen everywhere in our country, spoiling crop after crop."

By this time Jack's eager face was smiling, and he was looking questioningly at Ben Gile.

"What kind of a beetle do you suppose it was?" asked the old man.

Nobody knew. At last Jack ventured, "Was it a potato-bug, sir?"

"Yes."

"Oh, of course!" shouted the children. "Why didn't we think of that? But you said we had never seen it."

"So I did," said the guide, "and I don't believe there is one child here who has ever carefully watched the potato-bug. And there's the carpet-beetle, whose babies eat carpets unless your mother tempts them with pieces of red flannel. And there's the searcher-beetle, with its pretty green or violet wing covers, who is always on the search for caterpillars. And there's the fire-fly, which is a soft-bodied beetle.

"And there's the very useful little beetle we call the ladybug, which is not a bug, but a beetle. The ladybug is a great help to men who own fruit orchards in the West. All over the country are to be found little bugs called scale insects. These scales are very bad for trees, because with their long, slender beaks the scales pump out the sap. Sometimes they are so thick on the branch that they coat it entirely. You remember that I told you that one of these troublesome scales is the cottony-cushion scale, and that one day it was discovered that a lady-beetle from Australia liked these scales very much. So a great many of them were taken to California to eat the scales. The ladybugs eat little green aphids, too, and often Mrs. Ladybug will lay her eggs right in the midst of a family of aphids; and then the larvæ are surrounded by a hearty lunch when they come out of the egg. They eat the aphids, the scales, and sometimes the eggs of other insects."