U. S. n. A., B. r:. Rnl. as. Part II. D. F. I. I., July 6, 1907. 



PAPERS ON DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



THE SPRING CANKER-WORM. 



(Palencrita rcniata Wn-k.) 



By A. L. QUAINTANCE, 



//( Charge of Deciduous Fruit Insert Turest if/at ions. 

 INTRODUCTION. 



Two species of canker-worms in the United States, the spring 

 canker-worm {Paleacrita vernata Peck) and the fall canker-worm 

 {Ahophila povietaria 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 locally, infesting often but one or 

 two orchards in a neighborhood where conditions have been favorable 

 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 egg stage, or locally the 

 larvtip and moths may cling to clothing of persons, or may l)e dis- 

 tributed by teams visiting the infested orchards. 



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

 for many years and which are not sprayed with arsenicals furnish 

 ideal conditions for the multiplication of canker-worms when the 

 latter are once established. Frequently such orchards are defoliated 

 each s])ring, 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. While certain weather conditions and the 

 natural enemies of canker-Avorms ma}'^ 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 normal 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 pi-actice usually serving to keep them so reduced in num- 

 bers that their injuries are inconsequential. 



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