Charles S. Petrasch,
13 West Thirty-second Street, New York City.
I would like to exchange postmarks with any boy readers of Young People in the West. I am twelve years old.
Arthur S. Moore,
40 Third Place, Brooklyn, New York.
I would like to exchange postage stamps with any correspondent.
R. L. Preston,
P. O. Box 327, Lynchburg, Virginia.
Louise.—Your question, "Is the mosquito of any use in the great economy of nature?" has often been asked by many older and wiser than you, for it is not generally known that in their larval state mosquitoes form an important branch of nature's army of tiny scavengers. The larvæ live in the water of stagnant pools and marshes, and feed upon particles of decaying matter, and as their number is so very large, the amount they devour is considerable. By thus purifying the water they destroy the miasma which would otherwise arise and pollute the atmosphere to such an extent that no human being could breathe it with safety. The value of the work accomplished in tropical countries by these tiny scavengers is very great. It is estimated that the air of certain marshy regions would be so poisonous that no animal higher than a reptile could breathe it and live, were their purifying influence removed. We do not know that mosquitoes in the winged state have any useful mission beyond that of depositing the eggs which produce the larvæ, but that alone saves them from being "nothing but a nuisance."