U. S. D. A., I',. K. Unl. OS. I'art II. D. F. I. I., July 6, 1907. 



PAPERS ON DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



THE SPRING CANKER-WORM. 



(I'alcdfritii rcnxita IVck.) 



I'y A. L. (^lAI.NTA.NCK. 



In Chnri/c nf Dcchluoiis Fruit liiscit I nnsthjdtionfi. 

 INTRODUCTION. 



Two species of oanker-wornis in the United States, the spring 

 canker-worm {Paleacnta rernata Peck) and the fall canker- worm 

 {AlfiophUa pometarid Harr.), are often very troublesome pests in 

 apple orchards, infesting also the elm, cherry, and, to a less degree, a 

 few other trees. These insects, though widely distributed, usually 

 occur in injurious numbers quite locall}', infesting often but one or 

 two orchards in a neighborhood where conditions have been favoi'able 

 for their development. The females of both species are wingless, 

 hence their dissemination is very slow. The insects are doubtless 

 distributed mostly on nursery stock in the Qgg stage, or locally the 

 larvae and moths may cling to clothing of persons, or may be dis- 

 tributed by teams visiting the infested orchards. 



Old orchards which have been in sod or have not been cultivated 

 for nuiny 3'ears and which are not sprayed with arsenicals furnish 

 ideal conditions for the multiplication of canker-worms when the 

 latter are once established. Freipiently such orchards are defoliated 

 each spring, with the result that the injury to the trees prevents the 

 formation of fruit buds, and after a few years of such injury the 

 trees will begin to die. AVhile certain weather conditions and the 

 natural enemies of canker-worms may often greatly reduce the num- 

 ber of these insects, energetic steps on the part of the orchardist are 

 usually necessary to insure the complete destruction of the pests and 

 to permit the trees to resume their nornuil fruit production. In the 

 great majority of cases, if not in all, canker-worms are practically 

 limited to orchards which are neglected as to spraying and cultiva- 

 tion, either practice usually serving to keep them so reduced in num- 

 bers that their injuries are inconsequential. 



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