Part 18

"There is one little fly, Mrs. Tachina-Fly, who is of some use. She is a cousin of the house-fly. She is of use because she chooses a queer place to lay her eggs--on the back of a young caterpillar. After these caterpillars grow and shut themselves up into a cocoon to change into a butterfly the little fly eggs hatch out into maggots. Of course they are hungry--all babies are; and finding the nice, fat caterpillar in the round house, like dutiful babies they eat what is set before them until the fat, tender caterpillar is eaten up. After they are satisfied they lie still in their brown skins and change into grown-up tachina-flies, and at last out come a lot of busy, buzzing, bothersome flies. It is rather hard on the caterpillar. But when we think what harmful, greedy things most caterpillars are, perhaps it is good that there are tachina-flies to eat them. Is it time for supper yet?"

"No, not yet," replied Mrs. Reece. "Do tell the children something about mosquitoes."

"If I had to choose between Mr. and Mrs. Mosquito, I should take Mr. Mosquito, for he neither bites nor buzzes, but attends strictly to his own business. Perhaps he thinks Mrs. Mosquito's voice pretty. Perhaps he likes to hear about her adventures. But most people do not, for they think Mrs. Mosquito a busybody, always going where she is not wished, always breaking up conversations, and always coming back after she has been plainly told that she is not wanted. Yet her singing is music in the ears of her husband. Perhaps if we had long, slender antennae, all covered with hairs, like his, we, too, might like her song. When she sings these hairs begin to tremble, to vibrate, and a little nerve in the antennae changes this trembling to sound.

"In every way Mr. Mosquito seems a more pleasant body. He eats very little, and contents himself with nectar. But she, knowing that excitement makes the blood flow faster, and being a hearty eater, begins her song gently at first, then louder and louder, nearer and nearer. Finally, with her long, slender, sharp stylets, she makes a hole in your cheek or your arm, pushes in her sucking-beak, and pumps up the blood. And there she sucks and sucks until her stomach is full or she is brushed off or killed."

"Where do mosquitoes lay eggs?" asked Jack, who was certain that everything in the insect world did lay eggs, as indeed everything does.

"In the water; any puddle will do. When the eggs hatch out they are funny-looking fellows, long, tapering bodies with a big head end. At the other end are two little prongs. This baby, like some other babies, is never quiet, but squirms and wriggles so that it is called a wriggler. Upon its thick head are two little tufts of hair. These it waves every moment, so that all the food which comes its way will go into its hungry little mouth. One of the prongs at the other end of the body is an air-tube, so that the baby mosquito has to stand on its head to breathe. It hangs head downward, and holds its air-tube above the surface of the water.

"When people pour kerosene upon the water the wriggler cannot get any air to breathe, and therefore dies. Within a few days the wriggler changes its skin three times; after the third change it looks very different, and is called a pupa. Now, instead of having an air-tube at the end, it has two on the back of the thorax. At the tail end are two flaps to help it swim. Even the pupa is never still a minute, but holds its air-tubes above the water's surface.

"When anything comes to disturb it, it uses its flaps and swims safely to the bottom of the pool. At the end of two days out of the pupa skin comes a grown-up mosquito. If it is a Mrs. Mosquito, she promptly begins to bite people and to carry about fevers or malaria from person to person. The bite of a mosquito may sometimes be as dangerous as the bite of a rattlesnake."

The children had been slapping the mosquitoes buzzing about on the piazza. "And now," said the guide, "before we go into supper, I will tell you a real and a true story. Mosquitoes sometimes carry sickness from one person to another until it spreads throughout a large city. We didn't realize how dangerous mosquitoes were till a short time ago. People had malaria, and were very ill with it. In some countries many died. Every one thought, however, that the malaria came in some mysterious way from the mists of the low-lying swamps and marshes. But one day some one happened to think it might not be in the marshes, after all; rather that it might be a certain little two-winged insect with a short, piercing instrument, which spent its babyhood days in these same marshes.

"And so two English doctors determined to find out the truth of the matter. In the faraway land of Italy was a place where thousands of people were suffering from this disease. There these doctors went and built a comfortable little house in the very worst place they could find. They were careful to screen every door and window, and to leave not a crack for a mosquito to crawl in.

"There they lived, always going into the house at sundown, shutting all the screen doors, but allowing the damp night air to pour in. It was this night air which every one supposed gave people malaria. But the two physicians in the snug little house, free from mosquitoes, kept well, strong, and happy, although the people outside in the other houses were very ill and suffering with chills and fever.

"You see, these little Anopheles, for that is their name, bite some one ill with malaria. Perhaps the next person they stab with their sharp needle is well. In this way they leave some of the poisoned blood in the wound. There is another illness which is a hundred times worse than malaria. This is called yellow fever. In some countries thousands of people died from this every year, and doctors did not know just how it was carried from place to place.

"Our Government appointed a commission to study the matter. Dr. Walter Reed, a surgeon of the United States Army, with three assistants, went to Havana and built a house, carefully screened, just like that of the English physicians in Italy. People thought that the fever was carried in the clothes and on the sheets of those who were ill. To prove that this was not so, these men wore the clothes of sick people, and even slept on the sheets taken from the sickbed. They did this disagreeable thing for twenty days, keeping the little house very warm, and shutting out the fresh air and sunshine. But in spite of all these things the men continued well and strong.

"They wanted to prove even more surely that it was a certain kind of mosquito which really did the harm. So they built another house. Everything in this house was pure and clean. The rooms were flooded with fresh air and sunshine. Half of the house was carefully screened and shut off from the other half. The men in the half that was screened kept perfectly well. Those in the other half let themselves be bitten by mosquitoes which had been in the houses where there was yellow fever. All became dangerously ill with the fever. Two of these brave physicians died of the fever while trying to find the cause, in order that they might save the lives of thousands of people."

"That is modern heroism," said Mrs. Reece, "and service of the highest sort. All humanity is indebted to those brave men. There is no doubt but that our Panama Canal could not be in progress to-day were it not for the extermination of the mosquito in the canal zone. Since we can never tell where a mosquito has been, or what kind of a mosquito it is, I suppose it is best to keep mosquitoes from biting, and always to keep them out of the house. And now, children, supper is ready, and after that games. Let us go to the dining-room!"

CAMPING OUT

At last the day, expected all summer long, had come. The children, Hope and Betty, Jack, Peter, and Jimmy, Mrs. Reece and Ben Gile, were gathered on the edge of the pond, their packs in the canoes, their paddles at bow and stern. Other guides had taken the food and tents ahead the day before. Their friends had gathered to bid them good-bye, and finally, amid the farewells, they were off, Jimmie in a canoe by himself, Jack and Peter paddling Mrs. Reece, and Ben Gile with the two little girls. Everybody was so excited that all talked at once, and nobody could hear any one else. Hope and Betty had never been camping before, and the boys meant to show the girls all the wonders of sleeping and eating out in the woods.

Finally they came to a "carry"--that is, a path leading from one lake to another, across which the food and canoes have to be lugged. The girls and Mrs. Reece carried the packs and food over, making several trips in order to do so; and the boys and the guide, crossing their paddles under the thwarts of the canoes and raising the blades on their shoulders, balanced the canoes and trotted swiftly over the carry. Nothing seemed any trouble that glorious, beautiful day--nothing too heavy, nothing too hard. Betty and Hope could have skipped over every inch of the trail, and they were quite sure that they could have done all the paddling, too. And Betty did learn, in after years, not only to paddle, but also to carry her own canoe, for she grew to be a big, strong, athletic girl, with rosy cheeks and a quick, sure step.

Hour after hour they went from one pond to another. The ponds were larger and wilder at each crossing, and already they were in a wilderness of woods and lakes, and heard the whistle of the hawk, the scream of the lonely eagle, and the crazy cries of the loon. Every once in a while a big heron mounted lazily upward and flew off solemnly to a place where his peace need not be disturbed.

Although Hope and Peter and Jack lived all the year around in Rangeley Village, yet they had never been so far away from home before, and to them it seemed very wonderful. Even in the midst of it all, however, Jack did not forget the prize Ben Gile had offered. He hurried over carry after carry, and at the end of each one might be found flat on his face studying some little hill of ants.

At last, after travelling five hours, they came to a halt, ravenously hungry. Dinner was cooked and eaten, and then, after dinner, they began their long ascent of Saddleback, for they were going to a lonely little pond on the second highest mountain in the State of Maine. There, at Camp-in-the-Clouds, was a cabin in which Mrs. Reece could sleep, and the girls, too, if they wished, although they declared that they would not.

Up, up the hill they trudged, stepping over blow-downs, following their footing carefully, and watching with interest the little animals that scampered out of their way. But never did packs grow so heavy, and at last Mrs. Reece, who was carrying nothing but Jack's camera, sat down panting and laughing.

"I can't go a step farther," she declared, "until I catch my breath."

"This is a good place to rest," assented the guide. "Some deer found it so this morning, I think. Here, catch that butterfly, Jack!"

In a flash Jack had caught the butterfly, and brought it, gently, to Ben Gile.

"You don't see this fellow up here often. Who knows the difference between a butterfly and a moth? No one? Well, that is because most children are going to bed about the time the moth begins to fly. Doesn't any one know? You have all seen moths and butterflies? Well, well, well!

"The first thing you see is that when the moth lights on the edge of a flower-cup, instead of holding the wings up above the body, as the butterfly does, it spreads its wings flat over the body. Then a butterfly has little knobs at the tips of its slender antennae, while the moth has slender ones without knobs, or pretty, feathery ones that look like plumes."

"I supposed," said Peter, "that moths and butterflies were just the same, except that moths will fly into the house and burn their wings on the lamps." Peter didn't in the least care about moths and butterflies. He was longing to get to the top of the mountain, but he was too polite to seem impatient.