ZEUGOPHORA SCUTELLARIS 251 



The entire body is sparsely bristled, as indicated in figures 

 2 and 3. There are two pairs of bristles on the lateral margins 

 of the head. The ventral surface of the head bears four pairs. 

 The first thoracic segment has three pairs of bristles situated 

 dorsally, and two laterally. Four longitudinal rows of bristles 

 occur on the dorsal surface of the larva and two rows on the 

 ventral aspect (figs. 2 and 3). Each lateral prominence is 

 tipped by a strong bristle. Figure 4 shows the arrangement of 

 the bristles on the abdominal segments as seen in cross section. 

 Most or all of these bristles apparently assist in locomotion. 



In pointing out the characteristic features of the larva which 

 are most readily recognized one should perhaps call attention 

 to the depressed body, the strongly developed lateral projections 

 of the abdominal segments, and the arrangement of the bristles, 

 all of which can be seen at a glance. 



According to Professor Aven Nelson of the department of 

 botany at the University of Wyoming, the larva prefers Populus 

 acuminata but is also found upon other species in the West. He 

 writes as follows: 



I beg to state that the larva seen :s to prefer Populus acuminata 

 (Rybd.), the Colorado cottonwood, though I am inclined to think that 

 it occurs in the leaves of other species. The species native along our 

 streams is P. augustifolia (James), and in son-e of the lower altitudes 

 of the state there is also a broad-leaved cottonwood, P. occidentalis. 

 The latter I am quite sure is infested with the beetle but I am not 

 sure that P. augustifolia is. 



In Europe, according to Suffrain, the adult beetle Z. scutellaris 

 feeds upon Populus nigra. 



THE PUPA 



The pupa is strikingly like the imago in anatomical features, 

 though the parts are less sharply and gracefully outlined. This, 

 of course, is the usual condition of pupae in general, and is to be 

 expected in an immature and quiescent insect (see fig. 7). 



The pupa is yellowish or straw colored. At first there is no 

 indication of the dark pigment of the adult but before the final 

 metamorphosis the antennae and elytra begin to take on a 



