THE PEAR LEAF-WORM. 



19 



The larva shows no preference for any one part of the leaf. The 

 parenchyma and main or lateral veins — even blister-mite galls, when 

 these happen to be present — are consumed in turn as met with during 

 the continuous circular travel of the larva. A spot of arsenate of 

 lead reached in its path of travel becomes part of its food. The larva 

 does not change its course or eat around it because of a dislike for 

 the taste of the poison. 



The larval period occurs at a time when spraying is done for more 

 serious pests of the pear. Spraying specifically for its control would 

 coincide with the first application of spray for the codling moth, 

 when the blossoming period is about over and two-thirds of the petals 

 have fallen. The formula of arsenate-of-lead spray used for the 

 latter is quite as effective for the pear leaf-worm. 



CALIFORNIA EXPERIMENTS. 



In California, when pear orchards are infested with pear thrips 

 (Taeniothrips ivjri Daniel), the Government formula of distillate-oil 

 emulsion and nicotine^ used for the control of the pear thrips larva 

 is usually applied at a time when the pear leaf-worms are about all 

 hatched, and is also effective, as a contact-spray control, for the 

 latter. 



Therefore, in pear orchards well taken care of, when spraying 

 for the codhng moth has become as much of an indispensable practice 

 as that of plowing and cultivating, the pear leaf-worm has less 

 chance of becoming a pest of economic importance, and its control can 

 be considered as correlative with that of both the codling moth and 

 the pear thrips. 



Table XVI. — California spraying experiments indicating degree of efficiency of different 

 forrardas against the pear leaf-worm, Apr. 29 and 30, 1913. 



Tree sprayed and spray material used. 



Number of pear leaf-worms. 



Dead. 



Alive. 



Sick. 



Per 

 cent 

 dead. 



Per 

 cent 

 alive. 



TreeXo. 1: 



Lead arsenate 4 pounds, water 100 gallons 



Tree r 0.2: 



Lead arsenate 4 7>oimds, fish-oil soap 10 pounds, 40 per cent 



nicotine sulphate 1 '1600, water 100 gallons 



Tree No. 3: 



rish-oll soap 10 pounds, lO j)pr cent nicotine .sulphate 1/1000, 



water IfX) galloas 



TreeN'o. 4: 



Lead arsenate 4 pounds, flsh-oil soap 10 pounds, 40 per cent 



nicotine sulphate 1/lBOf), water 100 gallons 



Tree No. 5: 



Lead arsenate 4 pounds, flsh-oll soap 10 pounds, water 100 



gallons 



Tree No. 6: 



I-ead arsenate 6 pounds, water 100 gallons 



Tree No. 7: 



Yhh-oW soap 10 pound.s, 40 per cent nicotine sulphate 1/1000, 

 water UXJ gallons 



91 

 100 

 f)0 



KSi 



0(ii 

 97J 



I Ffjstxir, 8. W., and Jones, P, R. How to Control the Pear Thrips. U.S. Dopt. Agr. Bur. Ent.Clro. 

 131. 24p.,15ng. Kill. 



