Note 3 — Chapter VII

These insects are always much worse, and more numerous, when the spring is backward, and the floods are higher than usual. From close observation, I believe the larvae are deposited during high water on the rocks, when, as soon as the water falls, the heat of the sun hatches the insects. I have remarked large stones, which had been under water during the flood, covered over with small brown coloured cells, exactly the shape, and very little bigger than a seed of buckwheat. From out of these cells, on a sunny day, the flies rise in clouds, for they bite through the envelope, and emancipate themselves. Being provided with a sharp appetite, they will attack you the minute they are at liberty. These pests begin to appear between the 10th of May and 1st of June, according to the earliness or lateness of the season. Towards the end of June, numbers of small dragon-flies make their appearance, which soon eat up all the black-flies, to which repast, you may be sure, they are heartily welcome.