REPORT OF THE STATE ENTOMOLOGIST I9II 91 



gressed farther. Furthermore, this affection was uneven and varied 

 greatly within a few inches, indicating that it might have resulted 

 from some external application. This was true also of the tree cut 

 down. The tips of the branches and the trunk below the limbs had a 

 green, apparently healthy inner bark, while much of the inner bark 

 between these extremes had turned brown and was dead or nearly so. 

 We explain this condition by holding that the thicker bark of the 

 trunk would succumb less quickly to an injurious application 

 than the thinner bark just above. The smaller limbs, especially 

 at the top of the tree, escaped serious injury because of the 

 difficulty of spraying them thoroughly. The lesser injury to 

 the later sprayed trees is probably due to the increased pressure 

 of the sap hindering the penetration of the spray material. It 

 is well recognized among entomologists that bark borers work- 

 ing near the middle of the trunk of the tree, namely, near the 

 base of the larger limbs, may girdle the trunk at this point and 

 cause a successive and rather rapid death of both extremities of 

 the tree. We have repeatedly seen this in the case of bark 

 borers 1 working in the trunks of white pine, and the same pro- 

 cess may be observed in hickories succumbing to the injuries 

 of the deadly hickory bark borer, 2 a pest now very prevalent in 

 the vicinity of New York City. The spray material appears to 

 have girdled limbs and trunks by destroying the vital inner bark 

 and produced a condition similar to that resulting from bark 

 beetle attack. These insects can not be held responsible for the 

 injury, since the great majority of the affected limbs and trunks 

 show practically no indications of insect injury. 



6 It is our opinion that the trouble is largely if not entirely 

 due to injury caused by the material sprayed upon the trees. 



7 We would advise the prompt removal of the dead trees and 

 the early burning of the wood so as to prevent ' pin-hole " 

 borers or Ambrosia beetles breeding out and possibly causing 

 serious trouble later. We would favor leaving trees showing 

 fair signs of vigor till it was evident that they were beyond 

 hope. 



8 The leopard moth is well distributed throughout the city 

 and, if allowed to multiply freely, may ruin many trees. A 

 judicious cutting out of the borers and the destruction of the 



1 1 p s sp. 



2 Eccoptogaster quadrispinosus Say. 



