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The eggs are usually laid in the afternoon after 4 o'clock. When 

 ovipositing the insect alights upon the water at a place where a mass of 

 alga? exists. After walking around for a brief time, it finally extrudes 

 the eggs one after another, at the rate of about one per second until five or 

 six have been laid : it then walks a short distance away and then deposits 

 a few more. It has thus far been impossible to determine the number 

 laid by a single female, but counts of the eggs found in the ovaries and 

 oviducts of new females show it to be seventy-five to one hundred and 

 fifty, the average being about one hundred. 



Larva (PI. I, fig. 3). — The larvae hatch in from thirty-six to sixty hours from 

 the time of oviposition, the period of incubation depending' upon the temperature. 



The egg shell in hatching splits longitudinally on the upper surface, somewhat 

 in the manner of the eggs of Museidse, the small piece breaking out and the shell 

 afterward shriveling and rolling up. The young larvae are pale gray, almost 

 transparent and have a white spot on the anterior area of the thorax. The head 

 is marked by a prominent, black band extending around the entire posterior 

 margin and there are a few dark brown markings on its surface. The dark, 

 triangular spots before the eyes persist throughout the larval period and are the 

 beginnings of the adult compound eyes. This may easily be seen just before 

 the last molt and when the pupa has formed within the larval skin. 



The full grown larva (PI. I, fig. 3) is greenish-gray, the abdomen is dorsally 

 of this color, slightly darker near the median line. The region around the 

 anterior dorsal and ventral portions of the thorax has a decidedly blue color 

 subcutaneously. There is a small, transverse, black tergite between every two 

 abdominal segments. These tergites appear at first sight to be the result of 

 great transparency and the consequent visibility of the stomach and intestinal 

 contents, but they are of course cutaneous. The ventral surface of the thorax 

 and abdomen is jjale bluish-green-gray. 



The head is light buff, with the following dark brown markings above: The 

 small, round eyes at the lateral prominences; a large subtriangular band, repre- 

 senting the compound eyes of the adult in front of each eye; a narrow band around 

 the posterior rim of the head; a transverse, broken, wavy band five-eighths the 

 distance across the top, before the eyes; a Y-shaped line medially, opening ante- 

 riorly and connected posteriorly with the band on the posterior rim of the head ; 

 a small, triangular, median dot between the legs of the V; a smalt, round dot 

 behind the eye, halfway from the posterior margin. 



On the underside, the head is marked as follows: A large, brown patch on the 

 ventro-lateral area posteriorly; a fureula-shaped mark, its apex at the mouth, 

 extending posteriorly nearly to the margin; a small dot at the basal angles of the 

 labium. The tips of the mandibles are black. (PI. 1, fig. 5.) 



The labial plate is of peculiar structure, being bilaminate, the proximal lamina 

 has 9 teeth, the external lamina 5. A thin, chitinous prolongation of the cusps 

 extends into the head and serves as a brace. (PI. II, fig. 4.) 



The labium is composed of a movable portion which has 15 very stout, blunt, 

 curved bristles along its margin and is covered with smaller, scale-like processes 

 extending also to the elypeus. (PI. II, fig. 2.) 



Dorsally on each of the second to sixth abdominal segments, midway between the 

 median line and the lateral angle, is a small tuft of stellate hairs, used for 

 supporting the larva horizontally beneath the surface film. When it comes to 

 the surface these hairs spread out, engaging the film. Each abdominal segment 



