October, '19] PETERSON: APHID EGGS 363 



and meet the major demands in orchard fumigation, A limited stock 

 of 22 cubic centimeter graduated attachments would assure a correct 

 deUvery to those few fumigators who occasionally use 120 to 125 per 

 cent schedules. 



The purchase of liquid hydrocyanic acid should be by the pound. 

 One pound of 96 per cent hquid hydrocyanic acid (60° F., specific 

 gravity .702) measures 647 cubic centimeters and contains 36 charges 

 of 18 cubic centimeters. 



RESPONSE OF THE EGGS OF APHIS AVENJE FAB. AND APHIS 

 POMI DEG. TO VARIOUS SPRAYS, PARTICULARLY 

 CONCENTRATED LIME-SULFUR AND SUB- 

 STITUTES, SEASON OF 1918-1919 



By Alvah Peterson, Assistant Entomologist, New Jersey Agricultural 

 Experiment Station 



For three seasons, 1916-1919, careful observations have been made 

 on the behavior of three important species of plant lice occurring on 

 apple trees: A. avencB* Fab., A. pomi DeG., and A. sorhi Kalt. In 

 this paper particular attention is given to the beha\4or of the egg stage 

 of two species and their response to various chemicals and common 

 contact sprays. Additional observations have been made on the 

 influence of environmental factors, particularly evaporating factors, 

 on the eggs during the entire dormant season and also a distinct rela- 

 tionship has been found to exist between the killing efficiency of the 

 spray material and its spreading quality, but space will not permit a 

 report on these points at this time. The author's observations for 

 1916-1918, and also important observations made by Dr. T. J. Headlee, 

 may be found in the papers cited below. ^ 



During the past season, 1918-1919, many of the observations and 

 experiments, particularly spraying experiments conducted the pre- 



* Aphis avence Fab. referred to is apparently Aphis prunifolice Fitch and Aphis 

 sorhi Kalt. is Aphis malifolice Fitch. 



1 Headlee, T. J., 1916. Apple Plant Lice. In N. J. Agr. E.vpt. Sta. 3Sth Ann. 



Rept., pp. 494-.501. 

 Headlee, T. J., 1918. Some Important Orchard Plant Lice. In X. J. Apr. Expt. 



Sta. liuU. 328. 

 Peterson, Alvah, 1917. Studies on the Morphology and Su.scoptibihty of the 



Eggs of Aphis avcHfE Feb., Aphis pomi DeGecr, and Aphis sorhi Kalt. In 



Jour. Econ. Ent., Vol. 10, pp. .5.56-560. 

 Peterson, Alvah, 1919. Some studies on the Eggs of Important Apple Plant Lice. 



In N. J. Agr. Expt. Sta. Bull. 332. 



