OSBORN AND BALL — THE GENUS PEDIOPSIS. II3 



or color from the females, but the face is usually more strongly marked. 

 It would seem as if this group came nearer the European virescens than 

 either viridis or occidentalis , the former species possessing both a spot 

 on the face and the green color in the males. 



The members of this genus are widely distributed throughout the 

 North Temperate Zone, Europe possessing a larger number of species 

 than are at present known in America, none, however, being common 

 to the two countries though a number are closely related. 



They are almost exclusively tree feeding forms; the twelve North 

 American species of which the food plants are known are all tree feed- 

 ers, and most of the European species are so credited. 



In both countries the greatest number of species, and those the most 

 abundant and widely distributed, occur on the different species of wil- 

 lows ; besides these in this country the cottonwoods, the wild plums 

 and the honey locust each have two species, while of three species, 

 canadensis, occidentalis, and punctifrons, nothing is known as to food 

 plants. The two latter are closely related to willow feeding forms in 

 both countries, and it may be conjectured that they will also be found 

 to occur on willows. 



The larvae are all short, stout-bodied forms; the head is short and 

 straight, appearing from above as a narrow band in front of the broad, 

 straight-margined pronotum, which is slightly emarginate at the anter- 

 ior corners to receive the eyes; the abdomen is broad and short, 

 rounded on the lateral margins and dorsally carinate. In color they 

 usually mimic some part of the tree on which they feed and are detected 

 with difficulty when at rest. 



The larvae and adults are often very nearly alike in color, but the 

 characteristic anterior angle of the adult is entirely wanting in the larvae, 

 those with acutely angled heads, having in the larvae as short, straight 

 heads as their blunter headed relatives. The only noticeable difference 

 is a slightly increased width between the eyes, the anterior angling of 

 the pronotum and the consequent production of the head taking place 

 entirely during the change to the adult. In this respect they agree 

 with the Bythoscopus larvae, and both forms show a much closer rela- 

 tionship to Idiocerus through their larvae than would appear from the 

 adult structure. On the other hand Agallia, though closely resem- 

 bling Idiocerus in adult characters, seems to depart most widely from 

 it in the larval stage. 



All the species in which the life history is known are single-brooded. 

 The larvae appear during early summer and usually mature by the last 



