238 THE CANADIAN ENTOMOLOGIST 



on the median line, the distal margin with a row of comb-like bristles attached 

 to the ental surface, two long discal and two long lateral setae, the two groups 

 forming a transverse line, and four marginal setae; the mandibles tridentate, 

 the two inner teeth subsequal, the outer one much shorter; the thorax and 

 abdomen black above except at the sutures and with fine whitish fuscous lines 

 dividing the black into distinct areas — there is such a line on the meson of 

 the notum of the three thoracic segments and a line on each abdominal segment 

 dividing it into two parallel transverse bands, the posterior being the longer; at 

 the end of each of these bands a subquadrangular spot, and laterad of each anter- 

 ior spot another subsequal in size which bears the spiracle, and laterad of the 

 spiracle a much larger spot as long as the width of the segment," (bearing two 

 comparatively long hairs; the last abdominal segment bears a row of long fine 

 hairs on the posterior edge and the dorsal black spots,, on this segment are 

 fused.) "The sternum of the thorax and abdomen pale except a spot on either 

 side of the thorax laterad of the legs and homodynamous spots on each ab- 

 dominal segment (all of the foregoing spots bearing one or two hairs,) a spot on 

 either side mesad of the spots just described (each abdominal spot bears a short 

 hair,) and a median broad spot; and the last ventral abdominal segment with 

 a well developed proleg. legs blackish except at the sutures." (In many speci- 

 mens the lines dividing the segments are decidedly yellow giving the larva a 

 banded appearance dorsally. In others these lines and the lines dividing tbe 

 black areas are indistinct and the entire dorsal surface appears black. The 

 ventral surface is usually yellowish and the median brownish to black spots 

 vary in area.) 



Pupa. "Length (5 to) 7 mm. Width, (2.6 to) 4 mm. Black except the 

 sternum of the thorax and abdomen, the apical segment of the abdomen which is 

 covered by the cast skin of the larva, the basal segments of the legs, and a median 

 tergal line which are yellowish; the legs, wing-pads and antennae not closely 

 joined to the body; the very young pupae are lighter (yellowish at first) In colour." 



Adult. This was described by Linnaeus in 1758 (Syst. Nat. p. 376). The 

 following redescription is by Blatchleye. 



"Oblong-oval, narrower in front, subdepressed. Piceous brown, finely 

 pubescent; thorax dull yellow, usually with three piceous spots; side margin, apex 

 and epipleura of elytra yellowish; imder surface and antennae piceous, the 

 basal joints of the latter partly dull yellow; legs pale. Thorax twice as wide 

 as long, sides rather strongly angulate; front angles small, prominent, hind 

 angles nearly obsolete; disk with median narrow depression and a larger one 

 each side which is densely punctured and piceous; surface otherwise smooth 

 or with a few coarse punctures. Elytra slightly broader behind, margins dis- 

 tinctly flattened, surface coarsely and rather closely punctate. Length 4.5-6 mm. 



DeGeer as early as 1775 gave an account of this insect in Memoires 

 pour servir a rhislone des Insects, vol. V, pp. 326-329, PI. 10, figs. 1-6, and 

 it has received attention since then from other foreign authors. 



Chittenden? states that arsenicals are quite effective remedies in checking 

 the beetle on willow and for aquatic plants suggests flooding together with a 

 few drops of oil on the water to destroy the floating insects. If this is not possible 



6. Loc. cit. 



7. Loc. cit. 



