TWO LEATHOPPERS INJURIOUS TO APPLE NURSERY STOCK. 29 



from the abdomen. Numerous parasitized leafhoppers were collected 

 but no adult parasites were roared successfully. 



A. Giard (24), in 1889, reported the diyinid ApTidopus meJaleucus 

 Dalm. and the pipunculid Ateleneura spuria Meig. as parasites of 

 Typhlocyha rosae in France. 



Among the predacious enemies of this insect, mites, spiders, and 

 coccinellid and syrphid larvae have been noted feeding on the nymphs 

 to a limited extent. 



Wilson and Childs (27), in 1915, recorded the larva of a green lace- 

 wing, Clirysopa sp., as preying on young nymphs in Oregon. The 

 same authors list a dragonfly and a scatophagidfly as predacious 

 enemies of adults. 



REMEDIAL MEASURES. 



The apple leafhopper, Empoasca mali, is one of the most difficult 

 of all leafhoppers to combat successfully, especially because of the 

 wide range of its food plants. In nurseries, however, this species con- 

 fines its attack chiefly to the foliage of the apple, and if the hoppers can 

 be reduced in sufficient numbers on this plant the danger of infesta- 

 tion from other host plants will be very small. 



Little actual work has been done in dealing with the remedial 

 measures to be used against this pest. One of the most frequently 

 recommended methods which many writers have suggested as a 

 means of controlling this leafhopper in nurseries is the use of sticky 

 shields to catch the winged adults as they are jarred from the trees 

 along the nursery row. The use of such a device has never proved 

 satisfactory and it is impracticable when employed on a large scale. 



Spraying with contact insecticides against the apple leafhopper 

 has been generally advised. Weiss (19) suggested spraying with 1 

 pint of "black-leaf 40" to 100 gaUons of Pyrox. But in general the 

 recommendations have been so indefinite and vague that little value 

 can be attached to them. In order to clear up the confusion which 

 has existed in regard to the treatment for this insect, spraying experi- 

 ments, based on the life-history studies, were carried out. 



SPRAYING FOR THE FIRST BROOD. 



Spraying experiments against the nymphs were conducted in the 

 nursery of Hoopes Bros. & Thomas Co. at West Chester, Pa. Tests 

 on a smaU scale were made, the spray being applied with a compressed- 

 air sprayer and an angle nozzle at a pressure of 60 pounds. Larger 

 plats were sprayed with a machine owned by the nursery which 

 consisted of a double-acting hand pump capable of 100 pounds pres- 

 sure and a 50-gallon galvanized tank set on a truck narrow enough 

 to allow it to pass between two rows of trees. "Set nozzles" on an 

 arrangement of pipes at the rear of this outfit were used, the nozzles 



