290 



pTTTJ.ETTNT OF THE BUREAU OF FISHERIES. 



The eyes are large, light reddish-brown in color, and widely separated; the antennae extend 

 diagonally outward and backward to the edge of the elytra; the maxillary palps are short and reach just 

 beyond the first legs. The femora of the first and second legs are at an angle of 45° with the body axis, 

 the tibise and tarsi are nearly in a straight line and overlap at the center of the body; the femora of the 

 third legs are at an angle of 90° with the body axis, or drawn a little farther forward than that; the tibiae 

 and tarsi are in a straight line and overlap as in the other legs, their tips reaching the middle of the 

 penultimate abdominal segment (fig. 48). 



The following table gives the time spent in the pupal chamber before pupating and the length of the 

 pupal stage in 10 specimens: 



Entered chamber. 



Pupated. 



July 13. 

 July 17. 

 July 19. 



July 17. 

 July 22. 



Emerged. 



July 18. 

 July 23. 

 July 24. 



July 23. 

 July 26. 



Entered chaniber. 



1920. 



Aug. 6 



Aug. 8 , 



1921. 



July 14 , 



July 18 



July 19 



Pupated. 



Aug. 8.. 

 Aug. 9 . . 



July 17.. 

 July 20. . 

 July 21.. 



Habits of the adult. — The hind legs of this species are very heavily fringed with swimming setae, and 

 hence it can swim rapidly and with much agility. It is also the best jumper of all the beetles studied 

 with the exception of Thermonectes omaticolUs, and the jumping is accomplished by the hind legs. This 

 beetle is found in every fishpond except 6D, and could probably be found there if the search were made 

 persistent enough. Its small size makes it harmless to the fish, and in its turn it serves as food for 

 fish, frogs, and some of the other beetles. 



Description of the adult. — General outline ovate, nearly elliptical, but somewhat narrowed posteriorly 

 and strongly depressed. Total length 6 mm., greatest width 3.50 mm. Thorax very short, more than 

 three times as wide as long and without widened margins; scutellum practically invisible; elytra widest 

 near the center, obliquely truncated anteriorly and posteriorly, with one or two rows of minute punctures. 

 Tarsi of the first two pairs of legs in the male enlarged and armed with spongy, prehensile hairs, two rows 

 on the basal joint and one row on the second and third joints. The coxae of the third legs are expanded 

 into broad processes, concealing the coxal cavities. The coxal plates in the male are furnished with a 

 stridulating file, whose ridges begin at the inner margin near the center and extend outwards and back- 

 wards. The third legs are much flattened and armed with two rows of long swimming setae ; the spines on 

 the inner margin of the tibia near its distal end are unequal and distinctly emarginate at their tips. The 

 antennae are cylindrical, filiform, and 11- jointed; the mandibles have a wide terminal margin, which 

 is only slightly reentrant, with an acute ventral tooth and a blunt dorsal one. The maxillary palps are 

 four-jointed, somewhat club-shaped and rather short; the labial palps are very short and two-jointed. 

 The head, thorax, and under parts are reddish-yellow, the elytra black, each with four submarginal spots 

 and three basal lines of greenish-yellow. 



Laccophilus proximus Say. Figures 40, 42, 45, 47, 49. 



LaccopMlus proximus (Say, 1825, pp. 101 and 514). 



Eggs. — In this species, as in the preceding one, the eggs are probably deposited singly* in the stems 

 of water plants. 



Habits of the larva. — This larva has the same habits and eats the same food as the maculosus larva, 

 but is much less cannibalistic. Indeed, not once did it betray any such tendencies, and when the two 

 species were kept together, although the maculosus larvae attacked one another and also killed and ate 

 the 'proximus larvae, the latter never retaliated. 



Description of the larva. — This species is considerably smaller than the preceding for two reasons — 

 the first three and the last abdominal segments are actually shorter, and then the larva keeps all the 

 segments telescoped even when suspended from the surface film during breathing. Hence, while 

 the maculosus larva averages about 8 mm. in length when fully grown, the proximus larva is only from 

 6 to 6.5 mm. long. 



Proximus is also much the darker of the two, the entire upper surface being dark brown, with the 

 margins of the sclerites nearly black. In the center of the dorsal surface of the head is a dark brown 



