108 INSECTS OF MASSACHUSETTS. 



The most common leaf-beetle of the family under consideration 

 is the blue-winged Chrysomela, or Chrysomela cccrultipennis of 

 Say, an insect hardly distinct from the European Chrysomela 

 Polygoni, and like the latter it lives in great numbers on the com- 

 mon knot-grass (Polygonum aviculare), which it completely strips 

 of its leaves two or three times in the course of the summer. This 

 little beetle is about three twentieths of an inch long. Its head, 

 wing-covers, and body beneath are dark blue ; its thorax and legs 

 are dull orange-red ; the upper side of its abdomen is also orange- 

 colored ; and the antennae and feet are blackish. The females 

 have a very odd appearance before they have laid their eggs, 

 their abdomen being enormously swelled out like a large orange- 

 colored ball, which makes it very difficult for them to move 

 about. I have found these insects on the knot-grass in every 

 month from April to September inclusive. The larva? eat the 

 lea.es ( f the same plant. 



Having described the largest, the most elegant, and the most 

 common of our Chrysomelians, I must omit all the rest, except 

 the most splendid, which was called Eumolpus auratus by Fabri- 

 cius, that is, the gilde , Eumolpus. It is of a brilliant golden green 

 color above, and of a deep purplish green below ; the legs are 

 also purple-green ; but the It et and the antenna are blackish. The 

 thorax is narrower behind than the wing-covers, and the rest of the 

 body is more oblong oval than in the foregoing Chrysomelians. 

 It is about three eighths of an inch long. This splendid beetle 

 may be found in considerable numbers on the leaves of the dog's- 

 bane {Apocyivnn Androscrmifolium), which it devours, during the 

 months of July and August. The larva; are unknown to me. 



The fourth family of the leaf-eating Chrysomelians consists of 

 the Cryptocephalians (Cryptocephalid;e), so named from the 

 principal genus Cryptocrphalus, a word signifying concealed head. 

 These insects somewhat resemble the beetles of the preceding 

 family ; but they are of a more cylindrical form, and the head is 

 bent down, and nearly concealed in the forepart of the thorax. 

 Their larvas are short, cylindrical, whitish grubs, which cat the 

 leaves of plants. Each one makes for itself a little cylindrical or 

 egg-shaped case, of a substance sometimes resembling clay, and 

 sometimes like horn, with an opening at one end, within which 



