6o8 OCEAN, LAKE, AND RIVER. 



some substance in the bed of the water. Those that do not live in 

 cases make a pupa covering of decayed wood, or small stones. 

 WTien this metamorphose is completed, and they are ready to leave 

 • the water, they make with their mandibles a semicircular incision 

 in their covering, the head and the two first pair of feet are thrust 

 out, the rest of the body is partly drawn and partly vmggled out. 

 Now, as in the larvae form, they swim by using their feet, and make 

 their way with dexterity to the shore. In doing so I have seen 

 them swim across the stream, a strong current tending to carry 

 them down. In their struggles they would be part of the time on 

 the surface and part of the time under the water. When they se- 

 cure a landing place their appearance is somewhat peculiar. The 

 mouth parts, or a portion of them, and the two first pair of feet 

 are free, while the posterior feet and antennse are pressed to the 

 sternal surface, and over them the wings are folded, crossing at 

 the points. In ten or fifteen minutes after leaving the water they 

 cast off a thin parchment like covering, thus releasing all parts of 

 the body. They leave the water just before twilight, but will be 

 seen fluttering over the water at all hours. In the evening some 

 fly in dense swarms over streams and ponds. Many are noctur- 

 nal, flying only at night. They leave the water in June, July, 

 August, and September. A few species in the late fall ; a few on 

 warm days through the winter ; and some in the early spring, but 

 not in sufficient quantities to warrant their use as bait. The 

 forms that have been imitated the most, are named familiarly: 

 Stone, dark stone, grey stone, black June, general hooker, hod, 

 wren fly, raven, kingdom, preceptor, and governor. 



" The cow dung fly, {Scatophago stercoraria), so named on ac- 

 count of the lan'se feeding in the ordure of cows, belongs to the 

 section Diptera. It hybemates as pupae, buried in the earth. It 

 bursts open the chrysalis and comes forth the first warm days of 

 May. All the authors advise the use of this fly as bait on windy 

 days, thinking it was the wnd that brought it to the water. It 

 might be, if the wind always blew towards each indixndual stream. 

 It was, I know, a successful and popular bait for all streams, but 

 why, it was for a long time a puzzle to me. I was at length so 

 fortunate as to solve it. The females are short lived and seldom 

 leave the vicinity of the food for the young ; their imitations are 

 seldom used as bait. The males live until they are chilled by the 

 cold winds of the fall. They are greedy feeders, epicurean canni- 

 bals, feeding on their smaller sized cousins, fresh and juicy, catch- 

 ing them just as they are leaving the water. They hold them 

 with their anterior feet, fly to the bank, and sitting under the 

 shade of a leaf, suck the body dry. One evening I watched one 

 of these flies supping on six simuliums ; not being satisfied he 

 made a trip to the water for another, but there was a trout in wait- 

 ing and he sank to rise no more. The flies can be used success- 



