312 



BULLETIN OF THE BUREAU OF FISHERIES. 



stead of standing out rigidly. The anterior margin of the prothorax is not reentrant but is cut squarely 

 across. The head is shorter, and the eyes are in front of the center, the anterior ones being opposite 

 the bases of the antennae. The antennae and mouth parts are much the same as in the preceding species, 

 but the left mandible instead of having three teeth covered with processes has one large tooth with a row 

 of processes around its broad tip. A deep groove extends along the inner margin of the mandible from 

 this process to the base, and from the bottom of the groove project a row of irregular and unequal teeth. 

 The inner margin in front of the groove is also irregular. 



Description of the pupa. — The pupa is similar to that of striatus and is armed with the same jointed 

 styli, but the body is much narrowed and shortened posteriorly and is greener in color. The elytra, 

 wings, and legs are lengthened, the tips of the wings reaching the anterior margin of the penultimate 

 abdomen segment and the tips of the third legs projecting beyond the basal joint of the cerci. The 

 latter are much longer, and their terminal portion is more distinctly moniliform. The head is considera- 

 bly longer and narrower, and the maxillary palps project backwards to the bases of the third legs. 



Description of the adult. — This beetle is the same size as the preceding species. The thorax has 

 two black spots instead of the semilunar lines of striatus, and each elytron has 10 distinct black spots — 

 2 near the base, 4 in an irregular transverse line in front of the center, 3 in another irregular line behind 

 the center, and 1 near the tip. The basal joint of the antenna is shorter and more strongly curved, 

 and the second joint lacks the spine at its tip. The labium is longer and narrower, and the labial palps 

 are not as heavily armed with setae. This species is more restricted than the preceding in its distribu- 

 tion among the fishponds, but wherever it is found it furnishes excellent fish food. 



Berosus peregrinus Herbst. 



Berosus peregrinus (Herbst, 1797, p. 314). 

 Berosus peregrinus (Richmond, 1920, p. 48; pi. 10). 



A life history of this species, lacking the pupal stage, was given by Richmond, 

 and from it the following abstract has been condensed. 



Egg case. — Chestnut-shaped, cap end flat, cap continuous with a long narrow ribbon, the opposite 

 end rounded. Length of case 0.32 mm. ; width 1.20 mm. ; height 1.60 mm. Length of ribbon 4.50 mm. 

 Each case contained from 2 to 4 eggs which hatched in 6 to 8 days. 



Description of the larva. — General form similar to that of striatus, but the head and prothorax are 

 relatively much wider. Total length 5.60 mm.; greatest width (second abdominal segment) 1.68 mm. 

 Head ovate, a little wider than long; antennae nearer the lateral margins than in the two preceding 

 species; ocular areas circular and close behind the bases of the antennae. Prothorax the same width and 

 length as the head, meso and meta thorax slightly widened; body broadest through the second abdominal 

 segment, then rapidly narrowed. The lateral gills are as short as those of striatus, are much more slender, 

 and are trailed alongside the body like those of pantherinus. Color a uniform yellowish-white, the 

 chitin areas yellowish-brown. 



The mandibles are asymmetrical and resemble more closely those of striatus; the left one has three 

 larger teeth on the inner margin, covered with smaller ones. The basal joint of the maxilla is not as 

 long as in the other species and is armed along its inner margin with a row of five stout setae. The labium 

 is small, with two-jointed palps, each tipped with five short setae and one long one. 



Description of the pupa. — Schi0dte (1872) stated the distinguishing characters of this pupa as follows: 



Motory styli of abdominal tergites in fours; abdominal tergites with a small lateral tubercle on either side; spiracles not con- 

 cealed; abdominal pleurites not distinctly separated from the tergites; styli of pleurites very short and conical; lateral styli of 

 abdominal tergites very long and slender; prothoracic styli also long and slender; cerci elongate, tapering, crooked and distally 

 moniliform. 



His figure showed 26 pronotal styli instead of the 24 found in the two preceding species. 



Description of the adult. — This species is the same size as the other two. It is distinguished from 

 striatus by the facts that the second, third, and fourth abdominal segments in the male have a slight 

 longitudinal keel and that there is only one tooth instead of two in the middle of the notch on the fifth 

 segment of the abdomen. It is distinguished from pantherinus by the fact that the spots on the elytra 

 are very indistinct and are more or less fused in couples. 



It is much less abundant in the fishponds than the other two species, and only a few specimens 

 were obtained, but both the larvae and the adults furnish good fish food without being at all destructive. 



