WATER BEETLES IN RELATION TO PONDFISH CULTURE. 
273 
margin and not at the apparent end of the appendage; it is also hollow and communicates with a tube 
that opens into the mouth. Each maxilla is made up of a smaller basal segment and a larger second 
segment, which has a two-jointed palpus on its tip and a chitinous projection covered with setse at its 
inner distal comer. The labial palps are one-jointed. 
In the first legs the penultimate segment is prolonged at the inner distal comer, and the projection 
is toothed along the margin that faces the last joint, against which it shuts, forming a sort of chela. There 
is but a single terminal claw, with a short basal spine. 
Pupation. — From 20 to 25 days after hatching the larva is ready to pupate. It crawls a long distance 
from the water’s edge and forms its pupal chamber in rather dry mud. Into this it pushes for half an 
inch or more and there hollows out a spherical chamber about 5 mm. in diameter. It remains inside of 
this chamber from four to six days before transforming. The jointed spines are all discarded with the 
larval skin; of course many of them get broken during the formation of the pupal chamber, especially 
the long, narrow ends where the tracheoles are located. It would seem, therefore, as if the spiracles 
must begin to function before the transformation takes place. They become visible during this prepupal 
period, and with the disappearance of the tracheolar spines they assume their proper functions. 
Description of the pupa. — General form an elongated oval, 3.5 mm. long and 1.75 mm. wide. It is 
white or sometimes cream-colored, with a decided yellowish tinge, the eyes black or dark brown. The 
most striking feature is the position of the two front pairs of legs. In these the tibiae and tarsi are in a 
straight line and are folded tightly against the femur. The three are then turned forward until they 
stand at an angle of 45° with the body axis, the knees projecting a considerable distance on either side 
of the head. The anterior margins of the front legs touch the eyes, and the antennae are carried diag- 
onally across the anterior half of the eyes. Each knee of these two anterior pairs is armed with a stout 
spine; the head has two short spines between the eyes and one posterior to each eye; the pronotum has 
10 long, curved, simple styli on its dorsal surface, and a short jointed one on either side of the posterior 
margin close to the mid line. The meso and meta thorax have four short dorsal spines, two on each 
segment. Each of the first six abdomen segments has on its dorsal surface four long styli, two lateral 
and two dorsal, and between the latter a short spine on either side of the mid line. The seventh segment 
has four shorter styli and the last segment has six. 
The pupa lies on its back more than any of the other pupae studied, but also rests upon its ventral 
surface, with the body arched strongly upward, like the other pupae. When in this position, it is sup- 
ported on the spines at the knees of the first two pairs of legs and the styli on the last abdomen segment. 
Of 16 pupae reared to the adult stage, 12 remained in the pupa stage 12 days and four transformed at the 
end of the tenth day (fig. 9, p. 272). 
Habits of the adult. — The adults swim slowly and with considerable effort, moving the legs alter- 
nately as in walking. The tibiae of the first and second pairs of legs and the tarsi of all three pairs have 
long fringes of swimming hairs. In marked contrast to their labored swimming they walk and run 
on land with great agility, but can not, or at least do not, jump at all. They fly readily from pond to 
pond, but apparently can not cover very long distances. They live among the plants in shallow water 
and are not found in the open parts of the ponds. As far as observed they feed entirely upon Chara 
and Nitella. 
Description of the adult. — General form elongate-ovate, quite strongly convex; color pale straw- 
yellow with black markings; length 3.5 to 4 mm. Head with a large crescentic black spot between 
the eyes, punctate except in front of the black spot; eyes nearly circular in outline. Pronotum with 
a pair of basal black spots, rather sparsely punctate. Legs pale yellow except the femora of the third 
pair, which are dark brown ringed with yellow at their distal ends. Posterior coxse reaching the last seg- 
ment of the abdomen, punctate. Elytra each with 10 rows of punctures and a partial row between 
the third and fourth rows, and with seven or eight black spots more or less confluent. 
Genus HALIPLUS Latreille. 
Haliplus (Latreille, 1802, p. 77). 
Another genus of small beetles, which, both in the larval and adult stages, 
feed exclusively upon algae. They, too, like the members of the preceding genus, 
are yellowish or reddish in color with black spots on the elytra. They may be 
