Yet it must not be thought that the whole country is similarly and evenly filled. There can be no doubt that they flock and fly to the big moving creatures they see or smell. Maybe we had gathered the whole mosquito product of many acres. This is shown by the facts that if one rushes through thick bushes for a distance, into a clear space, the mosquitoes seem absent at first. One must wait a minute or so to gather up another legion. When landing from a boat on the Northern Lakes there are comparatively few, but even in a high wind, a walk to the nearest hilltop results in one again moving in a cloud of tormentors. Does not this readiness to assemble at a bait suggest a possible means of destroying them? Every one, even the seasoned natives, agree that they are a terror to man and beast; but, thanks to our flyproof tents, we sleep immune. During the day I wear my net and gloves, uncomfortably hot, but a blessed relief from the torment. It is easy to get used to those coverings; it is impossible to get used to the mosquitoes. For July 10 I find this note: "The Mosquitoes are worse now than ever before; even Jarvis, Preble, and the Indians are wearing face protectors of some kind. The Major has borrowed Preble's closed net, much to the latter's discomfiture, as he himself would be glad to wear it." This country has, for 6 months, the finest climate in the world, but 2 1/2 of these are ruined by the malignancy of the fly plague. Yet it is certain that knowledge will confer on man the power to wipe them out. No doubt the first step in this direction is a thorough understanding of the creature's life-history. This understanding many able mien are working for. But there is another line of thought that should not be forgotten, though it is negative--many animals are immune. Which are they? Our first business is to list them if we would learn the why of immunity. Frogs are among the happy ones. One day early in June I took a wood-frog in my hand. The mosquitoes swarmed about. In a few seconds 30 were on my hand digging away; 10 were on my forefinger, 8 on my thumb; between these was the frog, a creature with many resemblances to man--red blood, a smooth, naked, soft skin, etc.--and yet not a mosquito attacked it. Scores had bled my hand before one alighted on the frog, and it leaped off again as though the creature were red hot. The experiment repeated with another frog gave the same result. Why? It can hardly be because the frog is cold-blooded, for many birds also seem, to be immune, and their blood is warmer than man's. Next, I took a live frog and rubbed it on my hand over an area marked out with lead pencil; at first the place was wet, but in a few seconds dry and rather shiny. I held up my hand till 50 mosquitoes had alighted on it and begun to bore; of these, 4 alighted on the froggy place, 3 at once tumbled off in haste, but one, No. 32, did sting me there. I put my tongue to the frog's back; it was slightly bitter.