- 575 - 
tion of lime-nicotine dust should be made for the hard shell nymphs 
and adults of the first or second generation. 
HARTZELL, F. Z. (2407) 
1924. THE ESTIMATION OF DOSAGE FOE VOLATILE DUSTS: AN ILLUSTRATION OF 
THE VALUE OF CORRELATION MATHEMATICS TO ENTOMOLOGY. Jour. Econ. 
Ent. 17 (2): 279-285. 
The results presented are based upon experiments for the control 
of pear psylla in commercial orchards in western New York and the 
particular dosages apply strictly to 2 percent lime-nicotine dust. 
The methods of determining dosage were believed to be of general 
application for volatile dusts on different trees and for various 
insects (p. 285) . 
HUMDINGER, F. C. (2408) 
1924. EXPERIMENTS T7ITH CALCIUM CYANIDE AS AN INSECTICIDE. N. Y« State 
Hort. Soc. Proc. 69th Ann. Meeting, pr>. 134-138. [Abstract in Rev. 
Appl. Ent. (A) 12: 278. 1924.] 
Calcium cyanide, one part to three parts of ground talc as a 
carrier appears to be as effective as a 2 percent nicotine dust for 
the control of the pear psylla ( Psylla pyricola Forst.) and the grape 
leafhopper (E rythroneura comes Say. ) and if carefully applied will 
not injure the pear or grape foliage. 
PARROT T, p. J. (2409) 
1924. SOME SIDELIGHTS ON DUSTING AND SPRAYING PRACTICES. N. Y. State 
Hort. Soc. Proc. 69th Ann. Meeting, pp. 118-134. [Abstract in Rev. 
Appl. Ent. (A) 12: 277. 1924.] 
Adult pear psyllas ( Psylla pyricola Forst.) are susceptible to 
nicotine dusts. Nicotine dusts are not very satisfactory against the 
rosy apple aphid ( Anur aphis roseus Baker) and if used should be ap- 
plied when the blossom buds are in the pink stage, as the aphids are 
most susceptible at this period. 
FROST, S. 17., and CRAIGHEAD, E.M. (2410) 
1924. DUSTING FOR LEAFHOPPERS (EMPOA ROSAE L.) IN BEARING APPLE ORCHARDS, 
Jour. Econ. Ent. 17: 262-264, illus. [Abstract in Rev. Appl. Ent. (A) 
12: 312. 1924.] 
A 2 percent nicotine sulphate dust and 1 l/4 or 2 percent free 
nicotine dust killed a large proportion of the nymphs and adults. 
DAVIAULT, L. (2411) 
1926. LES CICADELLES ENNEKIS DE NOS PLANTES POTAGSRES. Sci . Agr. 5 (5): 
169-172. [abstract in Rev. Appl. Ent. (A) 14: 122. 1926.] 
