THE WATER-CRESS LEAF-BEETLE. 



17 



narrowed anteriorly and the a|)ex margined. The elytra have eight 

 punctate stria', Avith a short subsutural and subniarginal row of 

 l)unetures. The third joint of the tarsi is eniarginate apically. 



The present species measures a scant one-eighth of an inch in 

 length {''^ mm.), is shining bronzy black, and has the elytral intervals 

 apparenth" smooth, but in reality faintly rugulose when highly mag- 

 nified, while the thorax is microscopically reticulate. The original 

 description appeared in 1858." 



7'/ie i'g<j. — The eggs have not come under observation. They prob- 

 ably resemble those of the European Ph. armoracioi L., described by 

 P'ryer as " elongated oval and of a dark orange color." 



Fig. 5. — The water-cress leaf-beetle (I'lneiloii wruginosa) : «, adult; h, larva, from above; 

 c, same, from side; d, pupa. Enlarscd twelve times (original). 



The larva. — The larva appears somewhat like that of a related 

 genus, Galerucella, only that it is very much smaller. It is about 

 three or four times as long as wide, depending upon whether it 

 is somewhat contracted or fully extended. The head is subtruncate 

 in front, with the antenna^ lateral (in preserved specimens). The 

 head is shining black, and the remainder of the body very dark brown 

 or brownish l)lack relieved by lighter areas between the segments. 

 The first thoracic segment is a little wider than the head; the sec- 

 ond considerably wider than that, and the third widest, being nearly 

 as wide as the first two abdominal segments. The second abdominal 

 is widest, and at the same time the widest part of the body. The 

 surface is sparsely covered with long hairs placed on piliferous tu- 

 bercles, which are arranged some distance apart, as shown in figure 

 5, h. The tubercles on the sides of the dorsum are sometimes very 

 prominent, and the larva is able to extend these, possibly, at will. 

 From the abdominal segments large tubercular sections bearing hairs 

 at their summit extend on each side. The anal .segment is pale, like 

 the ventral surface, which bears dark i3iliferous tubercles. Length, 

 5 mm.; width, 1.2-1.5 mm. 



o Eut. Zcituniu', Stottin, Vol. .\i.\, pp. .".!)."). 80(!, 1858. 



