LEAFHOPPERS OF MAINE, 83 



TIhe Species' affecting forest trees, while a very great num- 

 ber and having a very wide disitrilbution over different kinds 

 of forest trees, are still so widely scattered that it is dififioult 

 to 'suggest any method's by which their numbers may be con- 

 trolled. Probably nearly every species of forest trees is subject 

 to the attack of some kinds of the leafhoppers and certain 

 species sudh as the birch, pine, wi'lloiw, etc., are affected by a 

 number of different kind.s which in some cases have become so 

 abundant as to cause serious injury and mo douibt are a con- 

 stant dirain upon the growth of the trees. While they do not 

 cause an immediate diestruction of the trees; it is easy to see that 

 such a drain going on constantly year after year during the 

 period' of growth must affect the rate of wood formation and 

 consequently provide a distinct factor in retarding the growth 

 of the forest croip. 



Tihis is per^haps at present a somewhat negligible factor be- 

 cause of present .methods of the lumbering or forest manage- 

 ment as there is iposisibly a mudh greater loss from wasteful 

 methods of cutting or from forest fires than can be charged 

 to these insects. However, this should be counted as one factor 

 in the successful growth of a forest crop and it is desirable 

 that the species be known and the ipanticular plants that they 

 affect shoiuild be determined and that their life history and 

 habits shall be determined as a basis for any possible general 

 measures that may be suggested from sudh definite knowledge." 



iFor park and shade trees the problem is somewhat different 

 and there are many cases 'wihere direct treatment may be avail- 

 able for the control of the injurious forms. Among the most 

 noticealble ones are the various species of Oncopsis affecting 

 the birch, this tree apparently being the favored food plant for 

 a number of different kinds. Often these swarm in large nurni- 

 bers and it is hardly possible to beat any individual birch: tree 

 d'uring the proper season without securing specimens of these 

 species. 



The conifers are aff'ected by several different forms but the 

 more distinctive ones belong to a related family, the Cercopidae, 

 and certain of these species, (Aphrophora) occasionally occur 

 in such great abundance that the growth of the trees must be 

 very seriooiisly retarded. Moreover, the punctures which they 

 cause may very likely serve as the points o/f entrance for vari- 



