•278 



Burke (H. E.). California Oak Worm. — U.S. Dept. Agric, Washing- 

 ton, D. C, Farmers' Bull, 1076, February 1920, 14 pp., 9 figs. 

 [Received 21st April 1920.] 



The food-plants and natural enemies of this moth [Phryganidia 

 californica] have already been noticed [R.A.E., A, vii, 381]. In 

 addition to native and introduced oaks, it attacks the American 

 chestnut {Castanea dentata) and blue gum {Eucalyptus globulus). Its 

 occasional appearance in such large numbers as to defoliate the oak 

 trees, and become a general nuisance by crawling everywhere, is due 

 to the reduction of its natural enemies during the periods when its 

 own numbers are few. There are two generations a year, the cater- 

 pillars being most noticeable in April and May and again in August 

 and September. The best method of control is to spray the trees 

 while the larvae are young with a mixture of 3 to 5 lb. of lead arsenate 

 paste, or half that amount of powder, dissolved in 50 gallons of water. 



The Outbreak of Locusts in Western Canada in 1919. — Agric. Gaz. 

 Canada, Ottawa, vii, no. 3, March 1920, pp. 218-220, 2 figs. 



An outbreak of locusts that occurred in certain sections of Manitoba, 

 Saskatchewan, Alberta and British Columbia in 1919 was the most 

 important from an economic view point since the West was developed 

 as an agricultural region. As soon as it was realised that the emergence 

 of young hoppers was unusually large, farmers were warned and 

 control measures were advocated. The infested areas were determined, 

 demonstrations of the action of poison-baits were given and later in 

 the season the new areas in which oviposition had occurred were 

 ascertained. The difficulties were enhanced by the fact that the 

 outbreaks were most severe in districts affected by the extreme drought. 

 As a result of the wide-spread application of poisoned bait and the 

 use of hopperdozers, however, thousands of acres were saved. 

 Investigations of the areas infested indicate that, unless unfavourable 

 weather supervenes, the infestation of 1920 will cover about twice 

 the area of that of 1919. In Saskatchewan it is estimated that wheat 

 worth upwards of £400,000 was saved by the measures practised. 

 Some 226 tons of poisoned bait were used, costing approximately 

 £5,000. 



Hopkins (A. D.). The Bioclimatic Law. — Jl. Washington Acad. Set., 

 Washington, D. C, x, no. 2. 39th January 1920, pp. 34-40. 

 [Received 26th April 1920.] 



The greater part of the contents of this paper has already been 

 noticed [R.A.E., A, viii, 87]. The measurement of the intensity of 

 the factors controlling this law can best be effected by observing tl.e 

 response of any given plant or other organism to a given environmental 

 influence, since all organisms that are adapted to it respond to such 

 influence in like manner. The organism not only records the influence 

 of all factors that are recorded by artificial instruments but also all 

 the other forces that affect life activity, which no instruments yet 

 invented can do. 



