182 



The cabbage aphis [Brevicoryne brassicae] has been more destructive 

 than at any time since 1913. Experiments demonstrate the dwarfing 

 effects of attack by this pest and the possibility of greatly reducing 

 its numbers by thorough spraying. 



Whetzel (H. H.). The Present Status of Dusting. — Proc. 2nd Ann. 

 Meeting N. Y. Hortic. Soc, 1920, pp. 45-75. [Received 10th 

 February 1921.] 



In an attempt to solve the much discussed question of dusting 

 versus liquid spraying for insect pests and diseases of fruit trees, 

 the author has gathered together a mass of data gained experimentally 

 in various parts of the United States and Canada, and under very 

 varied climatic and other conditions. The experimental evidence 

 thus obtained clearly indicates that dusting is quite as effective in 

 the control of apple scab and codling moth [Cydia pomonelld] as is 

 spraying. The opinion of many growers who have been experimenting 

 in dusting is quoted. There are, however, certain accessory problems 

 that require to be solved before dusting can be generally adopted in 

 place of spraying. One is the finding of an effective contact dust 

 that will kill sucking insects in general. One or two such preparations 

 show promise, but cannot yet be adopted for general use. There 

 still remains the problem of an effective dust for the San Jose scale 

 [Aspidiotus perniciosus]. Dusting machinery will undoubtedly be 

 greatly improved in the next few years, and other points, such as the 

 best time of day for operating, will be determined by experience. 



While not attempting to analyse the question of the comparative 

 cost of dusting and spraying, the author is of opinion that in view of 

 the lighter labour involved, dusting will prove the cheaper practice 

 of the two. 



Stahl (C. F.). Studies on the Life-history and Habits of the Beet 

 Leaf-hopper (Preliminary Paper). — //. Agric. Res., WasJiingto)i, 

 B.C., XX, no. 4, 15th November 1920, pp. 245-252, 2 plates. 

 [Received 12th February 1921.] 



The various stages of Eutettix tenella, Baker (beet leaf-hopper) 

 are described, and the life and seasonal history as studied in Idaho 

 and California are discussed [cf. R.A.E., A, vi, 480]. 



The most important egg-parasite is Polynema euteitixi, Gir., which 

 has at least nine generations a year, the complete cycle from adult 

 to adult covering about 35 days. Other egg-parasites are the hyper- 

 parasite, Abbella subflava, Gir., and Anagrus giraidti, Crawf. The 

 parasites of the nymphs and adults have already been noticed [loc. cit. 

 iii, 557]. 



Cotton (R. T.). Rice Weevil (Calandra) Sitophihis oryza. — Jl. 

 Agric. Res., Washingio)i, B.C., xx, no. 6, 15th December 1920, 

 pp. .409-422, 1 plate. 



During 1918 Calandra {Sitophihis) oryzae caused serious damage 

 to maize in the southern United States, involving a loss of approxi- 

 mately £6,000,000. The losses due to this weevil are particularly 

 severe in tropical countries where the weather conditions admit of 

 breeding all the year round. In Florida all stages of the weevil are 



