INSECT ENEMIES OF WESTERN FORESTS 



115 



are many species that work on the leaves of various western 

 broadleaved trees. 



The madrone shield bearer (Coptodisca arbutiella Busck) mines 

 the leaves of madrone and cuts out elliptical holes when construct- 

 ing the pupal cases. Commonly associated with it in leaves of 

 madrone is another leaf-mining species, Marmara arbutiella 

 Busck. 



The poplar leaf blotch miner (Phyllonorycter tremuloidiella 

 Braun) attacks the leaves of aspen and poplars and constructs ir- 

 regularly shaped mines between the upper and lower leaf surfaces. 

 During heavy infestations nearly all the leaves on the lower parts 

 of the trees are attacked, but infestation seldom extends above 50 

 feet. The damage results in premature shedding of the foliage. It 

 has been reported from California, Idaho, British Columbia, and 

 southern Utah and probably has a more extended range. When 

 mature, the larvae change to small black pupae within the mines 

 and then emerge as small drab-colored moths. Other species of 

 Phyllonorycter include P. salicifoliella Chamb., which works in the 

 under side of the leaves of willow, poplar, and cottonwood; P. 

 apicinigrella Braun, which works in the under side of willow 

 leaves; P. felinella Hein. (27), which works in the under side of 

 sycamore leaves in California ; P. incanella Wlsm., which works in 

 both sides of alder leaves ; and P. arbutusella Braun, which works 

 in the leaves of madrone. 



Figure 51. — Work of an aspen leaf miner (Phyllocnistis populiella) 



