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NEW YORK STATE MUSEUM 



trunk, not many penetrating to a greater depth than an inch. 

 Their burrows may become so thick as to girdle trees two or 

 three feet in diameter. An infested elm may be recognized by 

 the patches of unhealthy bark — in case of a bad infestation large 

 pieces become loose and scale off easily. The beetle is usually 

 less than J inch long, and of a dull slate color, with the thorax 

 and wing covers margined with dull orange (fig. 6). 



Fig. 6. — Saperda tridsntata (twice natural size) 

 NATURAL. ENEMIES OF ELM-LEAF BEETLE. 



The natural checks which serve so well, to keep thousands of 

 insects under control which otherwise would be very destructive, 

 are unable to reduce the numbers of this beetle to a relatively 

 harmless figure. One of the more important natural agents is 

 the fungus, Sporotrichum' entomopMliim Peck, which has been 

 observed developing on many beetles in this city. Like the dis- 

 ease of the chinch-bug, caused by the allied fungus, Sporot Helium 

 gldhulifei^um Speg., the one attacking the elm-leaf beetle requires 

 moist atmosphere for its development. Beetles in close breeding 

 jars or those found under the bark of trees and similar damp 

 places succumbed readily to the disease. On account of the cli- 

 matic conditions not being ordinarily favorable to the rapid 

 growth of this fungus, it has a relatively slight value as a natural 

 check upon the elm-leaf beetle. 



Several insects are known to prey either on this pest, its pupa 

 or larva. Three beetles, Platynus puncUformis Say, Quedius molo- 

 cMnus Grav. and CliauUognatJiiis marginatus Fabr., feed on this 

 species as recorded by Kiley. A fly, Cyrtoneura stadiilans Fall., 



