THE PEAR LEAF- WORM. 23 



Poison spray. — Four pounds lead arsenate to 100 gallons water. 



Contact spray. — Fish-oil soap 4 pounds; water 100 gallons; nico- 

 tine sulphate (40 per cent concentrate) 1 to 1,200; also the Govern- 

 ment formula of distillate-oil emulsion and sulphate of nicotine.^ 



In cases of ordinary infestation the contact spray such as is used 

 for thrips larvse or aphids will prove successful in controlling the larva 

 of the pear leaf-worm. When the infestation is severe and promises 

 the defohation of limbs or whole trees the poison spray should be 

 used. Tlie best time for apphcation is when the largest larvae are 

 about half grown and when the holes in the leaves are not larger 

 than one-half inch in diameter. At this time nearly all the eggs have 

 hatched. 



BIBLIOGRAPHY. 



(1) 1883. Cooke, Matthew. Injurious Insects of the Orchard, Vineyard, etc., p. 



120-122, fig. 98, 99. 

 Brief account of insect and habits in California. 



(2) 1896. Marlatt, C. L. Revision of the Nematinas of North America. U. S. 



Dept. Agr. Tech. Ser. no. 3, p. 122, 123, fig. 10. 

 Original description, erection of genus Gymnonychus. 



(3) 1915. EssiG, E. O. Injurious and Beneficial Insects of CalifoiTiia. Cal. State 



Comm. Hort., Supplement to the Monthly Bulletin, v. 4, no. 4, p. 360, 

 fig. 356, 357. 



Brief general account of occurrence and habits in California. 



1 Foster, S. W., and Jones, P. R. How to Control the Pear Thrips. U. S. Dep. Agr. Bur. Ent. Circ. 

 131, p. 8. 1911. 



