Let us now sit down and rest for an hour, and eat our lunch; the fish do not rise as freely as they did; perhaps later on they will be in the humour again. But what do I see sticking to the sides of that rail across the river; I must go and see. Well, really this is an interesting thing. An immense mass of flies, a few alive, but the greater number quite dead; and, look! a quantity of white eggs underneath them. Let us examine a fly; it is of a brown or tawny colour, and has rather long, diverging, colourless wings, marked with irregular brown spots. Why, there must be thousands of dead flies covering these eggs. What an odd idea! Presently up comes Mr. Collins from the farm near the bank of the stream. "Oh, sir, I know those flies quite well; they are oak-flies (_Leptis scolopacea_)." Certainly not, I replied, though they do somewhat resemble them in colour and appearance; but the farmer stoutly asserted he was right, and I did not think it worth while discussing the matter further with him. Mr. Collins is a good fly-fisherman; and fly-fishermen, unless they are naturalists, are generally very positive. How often have I tried to teach anglers that the May-fly does not come from a caddis worm; how often have I failed! Well, the two-winged fly I have just found in such thousands, with their dead bodies brooding over this mass of eggs, is known to entomologists by the name of _Atherix Ibis_; the females are gregarious, and, as we have seen, attach their eggs to rails, boughs, or other objects overhanging streams; each female, having laid her eggs, remains there and dies; shortly after comes another and does the same, and so on till immense clusters are formed. The larva, when hatched, falls into the water, its future residence; it is said to have a forked tail about one third the length of its body, and to "have the power of raising itself in the water by an incessant undulating motion in a vertical plane." I am not, however, acquainted with either larva or pupa, but hope to become so this summer. "It is very curious, papa," said Jack, "that the flies, after they have laid their eggs, should die there; why do not they fly away? Do any other animals do the same?" Yes, pretty much so. Some of the female insects of the genus called _Coccus_, scale insect, or mealy bug, common on the stems of various trees, to which they sometimes do incredible mischief, lay their eggs and die over them, the dead bodies of the parents forming coverings for the young. See how fast the green drake is appearing. Notice how it flies with head erect for a second or two, and then falls almost helplessly on the surface of the water.