WATER BEETLES IN RELATION TO PONDFISH CULTURE. 
331 
and kill another, even though food was scarce. The simple fact that they do thus herd together in such 
numbers shows an entirely different disposition from that of the other two species. In the ponds they 
fed readily upon snails, entomostracans, damselfly nymphs, mayfly larvae, and small tadpoles. In all 
other respects their habits were identical with those of the two preceding species. 
Description of the newly hatched larva. — This larva is 4 mm. long, including the mouth parts, and 
0.75 mm. wide. Head nearly quadrate, not appreciably narrowed posteriorly; fronto-clypeal suture 
distinct; antennal sutures wavy rather than straight, converging posteriorly into the shortest epicranial 
suture of the three species here described, only one-twentieth the length of the antennal suture. Frons 
triangular, the anterior side or base one-fifth shorter than the other two sides, the apex or posterior angle 
broadly rounded. Anterior margin of the head only slightly concave, the lateral expansions of the 
epistoma barely protruding beyond the clypeus. The latter has rather small teeth, larger than those of 
lateralis but not as large as those of gldber. The central one and the two outside ones are the same size 
and larger than the other four. The transverse row of six small spines are all about the same size and 
equally distant from the margin. The frontal margin of the epistoma also carries on either side a row 
©f 10 or 11 small spines, increasing in size outwardly, the largest one at the outer corner. 
The first (anterior) eye is larger than any of the others; behind the sixth eye stands a seta, and there 
is a row of four along each lateral margin of the head behind the eye area. The basal joint of the antenna 
is shorter than in the other two species and is only three-fifths longer than the other two joints together. 
The terminal joint is a little shorter than the second joint and less than half its diameter; the fingerlike 
appendage at its tip has apparently two segments. 
The mandibles are stouter than those of lateralis but not as stout as those of gldber. The distal 
tooth on the inner margin is like that in the preceding species, its bifid tip bluntly pointed, the teeth 
on its inner margin quite distinct. The middle tooth is not double, but is short, broadly triangular, 
and acuminate, and stands in the center of the groove. The proximal tooth is minute and stands on 
the ventral margin of the groove, its proximal edge running across to about the center of the groove. 
The two proximal teeth on the right mandible stand side by side, one on each margin of the groove. 
The maxillae are stouter than in the two preceding species but otherwise similar to them. The labium 
is relatively longer, the terminal setae of its palps reaching the distal end of the maxillary stipes. The 
mentum has convex sides, and its anterior corners are produced into short and acute spines. 
The mature larva. — When fully matured, the larva is 11 to 13 mm. long, 3.25 to 3.75 mm. wide. This 
larva may be recognized at once by the color pattern; along the median line of the dorsal surface of the 
head and curving backward from the eye areas on either side are broad stripes of orange-yellow, nar- 
rowed posteriorly. Between these on each side is a wide stripe of dark, cinnamon-brown, running 
from the base of each antenna back to the prothorax, and another wide brown stripe on either lateral 
margin behind the eyes. These stripes are all uniform in color and not spotted. On the prothorax 
in place of the longitudinal dashes of the other species there is a three-sided parallellogram on either 
side of the mid line, the anterior end lacking. The mesothorax and metathorax have dark brown 
sclerites like those of the other species but differing somewhat in shape. The abdomen is light brown 
dorsally, the margins of each segment slightly darkened, but without other markings. The lateral 
tracheae show through as a wide dark line along either side. 
This larva has a larger number of papillae along the sides of the abdomen and is more densely cov- 
ered with hairs than either of the others. The basal joints of the antennae remain less than twice the 
length of the other two joints together, and are comparatively stout. The labium is narrow but elon- 
gate, and the tips of the labial palps reach well beyond the distal tooth on the inner margin of the 
mandibles. 
Description of the pupa. — Total length, including the cerci, 6.50 mm., greatest width, through the 
bases of the second legs, 3.35 mm. Length of metatarsal spine, including the wide base, 1.75 mm. 
In the lateralis pupa this spine is 2.40 mm. long, and in the gldber pupa it is 3 mm. long. Length of cerci 
1 mm. This pupa differs from the two preceding ones in the following particulars: The space between 
the eyes is wider; the labial palps are longer; the metasternal spine is actually shorter, but its tip reaches 
the middle of the fifth abdominal segment; the tarsi of the second legs and the tips of the wings reach 
the middle of the sixth segment; and the tips of the third legs reach the anterior margin of the last seg- 
ment. The cerci are as slender as those of glaber but lack the spines on the outer margins. The meso- 
tibial and metatibial spines are less distinct. The duration of the pupa stage is four or five days, as 
in the other species. 
