WATER BEETLES IN RELATION TO PONDFISH CULTURE. 



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The last segment is prolonged backward on the dorsal surface into a short papilla, from beneath whose 

 base arise the divergent cerci, which are as long as the last three segments and are heavily fringed with 

 hairs. The entire surface of the last two segments is sparsely covered with short hairs, others are found 

 on the lateral margins of the other segments, and each sclerite bears a row of short spines along its pos- 

 terior margin. The legs are comparatively long and slender but are strong enough to support the larva 

 and are well fringed with swimming setae. 



The antennse are not on the dorsal surface but on the lateral margins of the head behind the bases of 

 the mandibles (fig. 39). Each is four-jointed, the three basal joints about the same length, the terminal 

 joint less than a fourth as long. The labro-clypeus has a peculiar fringe on its anterior margin, which 

 helps to identify the larva. It is made up of two rows of processes of the form shown in Figure 41 , one 

 row dorsal to the other. The processes of the dorsal row are much larger and longer than those of the 

 ventral row and alternate with them. 



The mandibles are long, slender, and grooved on the inner margin nearly to the base; when closed 

 they overlap more than half their length. In the maxillae the cardo is short and narrow, the stipes much 

 longer and wider, the palp three- jointed, the joints about the same length, while the galea is reduced 

 to a fingerlike process tipped with a sensory papilla and two small setae, and the lacinia is wholly wanting, 

 or may be represented by two stout curved spines inside the base of the galea. The tip of the stipes is 

 densely covered with short hairs. The labium is twice as wide as long, and the palps are attached to its 

 a,ntero-lateral corners; they are two-jointed, the joints about the same length and unarmed; there is no 

 ligula. Inside of each palp are a long hair and a stout jointed spine, and there is a pair of much smaller 

 simple spines near the mid line ; the mentum also bears a pair of small spines (fig. 46). 



The color of the living larva is a pale, greenish-yellow, unmarked on the ventral surface except on 

 the last two segments of the abdomen. On the dorsal surface, however, the following parts are more or 

 less brown: The mandibles, the frontal margin of the head, the lateral margins behind the eyes, the brown 

 widening as it approaches the thorax, a fleur-de-lis design at the center of the head, its lateral arms 

 extending outward and forward toward the eyes, and each of the dorsal sclerites. The anterior and pos- 

 terior margins of the sclerites are considerably darker in color than the rest of the surface, and in the last 

 two segments the brown and the deeper margins follow the sclerites around the body, becoming the 

 exceptional markings on the ventral surface mentioned above. There is a very narrow brown line along 

 the margin of each leg, another along the inner margin of each femur, and a ring around the top of each 

 leg joint. In some larvae the brown of the dorsal surface has a decided greenish tinge, while in others 

 it is deepened almost to black, especially along the margins of the sclerites, but in preservatives the green 

 entirely disappears and the black is considerably lightened. The contents of the digestive canal show 

 as a black streak through the center of the body and often surge backward and forward in rhythmic 

 pulsations. 



Pupation. — As would be expected from its locomotor ability, this larva travels from the water's edge 

 when ready to pupate as far as, and often farther than, the larger species. Having found a suitable 

 place, it biuTows into the earth and forms its pupal chamber less than half an inch beneath the surface, 

 often near a grass or plant stem. Having completed the chamber, the larva remains in it for one or two 

 days before pupating. 



Description of the pupa. — Length 5 mm., width 3 mm. The pupa is greenish- white in color, the 

 green being deeper through the center of the body, and is very frail. It must be handled with the 

 utmost care to avoid crushing it out of shape. It is not at all active, but lies inertly in the pupal cham- 

 ber in whatever position it may be placed. After a time, however, it readjusts itself and assumes the 

 usual position, the body arched upward into a semicircle, the dorsal surface uppermost, resting upon the 

 stout spines of the prothorax, the tips of the third legs, and the two strong cerci. 



The head is drawn into the prothorax and down onto the metathorax. There are three styli inside 

 the anterior end of each eye, two inside the posterior end and two on the base of the labrum. Along the 

 anterior and posterior margins of the pronotum are 12 or 14 styli on either side running inward from the 

 lateral margins, but leaving a wide vacant space in the center. On the dorsal surface near the center of 

 the segment is a single seta on either side. The mesothorax and metathorax have two styli at the base 

 of each elytron and a wing and a row of 10 or 12 on the posterior margin across the center. There is a 

 similar row across the posterior margin of each of the first seven abdominal segments, the lateral styli 

 being longer than those in the center; there is a row of five along each lateral margin of the eighth segment. 



