APPLE INSECTS — BUDS AND FOLIAGE 85 



necessary to renew the bands or apply two, as many of the 

 females may be able to cross the band over the dead bodies and 

 wings of the males, which may completely cover the sticky 

 portion. The use of these mechanical barriers or sticky bands 

 are especially recommended on very large, rough-barked elms, 

 or other trees that it would be difficult to spray or cultivate 

 thoroughly. 



If no effort is made to prevent the moths from ascending the 

 trees and laying their eggs, either in the fall or spring, the 

 voracious caterpillars can be killed with a poison spray in May. 

 This has been demonstrated many times, but only the most 

 thorough kind of spraying will conquer a hungry army of canker- 

 worms. The most effective work can be done by applying the 

 spray early, when the caterpillars are young and will thus suc- 

 cumb to a smaller dose of poison. Effective work has been done 

 with Paris green at the rate of 1 pound in 100 gallons, but an 

 arsenate of lead spray, 4 or 5 pounds in 100 gallons, has some ad- 

 vantages. For apple trees make one application just before the 

 blossoms open and a second after the petals fall ; if the work is 

 thoroughly done, further applications will be rarely necessary. 

 For shade trees, begin spraying as soon as the first leaves un- 

 fold or the young canker-worms are seen, which is usually early 

 in May. 



Under the modern system of fruit-growing, embodying 

 thorough cultural and spraying methods, canker-worms will 

 rarely find congenial conditions for their nefarious and destruc- 

 tive work ; in fact they now seldom attract the attention of 

 commercial growers. 



References 



Peck, Nat. Hist. Canker-worm. 1796. 



Harris, Insects Inj. Veg. pp. 332-343. 1841. 



Ohio Dept. Agr. Bull. 2. 1903. 



U. S. Bur. Ent. Bull. 68, Pt. II. 1907. 



Conn. Agr. Exp. Sta. Rept. for 1907-1908, pp. 777-796. 1909. 



