330 



than those treated with the latter mixture. Calcium arsenate with 

 lime-sulphur has caused noticeable yellowing of the foHage ; this 

 can be ehminated by adding 5 lb. of water-slaked or hydrated Hme 

 to each 40 gals, of thfe mixture when used for the after-blossom 

 sprayings. 



With such sulphide sprays as Kme-sulphur, barium tetra-sulphide 

 and sodium sulphides, calcium arsenate is the only poison on the 

 market that can be used without such chemical change taking place 

 between the sulphide and the poison as would result in injury to 

 foHage. On account of the apparent increase in the toxic value of 

 arsenicals that results from the presence of sodium salts, it has been 

 found desirable to decrease the amoimt of calcium arsenate used 

 with sulphide sprays to the proportion of | lb. calcium arsenate to 

 40 gals. Sodium sulphide solutions do not adequately protect calcium 

 arsenate against air, and in order to eliminate scorching where this 

 combination is used for the four sprays; 10 lb. hydrated or water- 

 slaked lime must be added to each 40 gals. 



With Bordeaux mixture, calcium arsenate has given great satis- 

 faction. While lead arsenate, on account of its adhesive qualities, 

 assists the fungicidal action of Bordeaux mixture more than calcium 

 arsenate, the difference in cost and greater convenience are both in 

 favour of the latter material. It is estimated that at the present 

 time Paris green and lead arsenate cost about two-thirds more than 

 calcium arsenate, while zinc arsenite costs about one-third more. 

 Buyers are warned against certain brands of calcium arsenate that 

 are coarse and gritty and low in arsenic, as these give bad results 

 with sulphide sprays. 



Ross (W. A.). Some Ladybird Beetles destructive to Plant Lice. — 

 Agric. Gaz. Canada, Ottawa, v, no. 4, April 1918, pp. 344-347, 

 2 figs. 



Among the Canadian Coccinellids that are of great importance in 

 the control of Aphids are : — Adalia bipunctata, Coccinella quinque- 

 notata, C. novemnotata, C. frifasciata, Hippodamia tredecimpunctata, 

 H. convergens, Megilla inacidata, and Anatis quinquedecimpunctata. 



SwAiNE (J. M.) & Sanders (G. E). The White-marked Tussock Moth 

 and its Control on Shade Trees and Orchard Trees. — Canada Dept. 

 Agric, Entom. Branch, Otta^va, Circ. no. 11, 7th March 1918, 

 12 pp., 9 figs. [Received 6th June 1918.] 



This comprehensive circular deals with Hemerocampa leucostigma,. 

 S. & A. (white-marked tussock moth), an account of which has already 

 appeared [see this Review, Ser. A, v, p. 174]. To control this pest in 

 the larval stage on shade-trees lead arsenate spray, at the rate of 5 

 to 15 lb. lead arsenate paste to 100 gals, water, is recommended. At 

 the time of hatching 5 lb. paste in 100 gals, water will kill the cater- 

 pillars ; if they are more than a few days old, 10 lb. will be required ; 

 while 15 lb. to the same volume of water must be used if they are 

 one-third grown. 



At intervals of from 7 to 10 years this insect appears in Canada 

 as an orchard pest. From early July till mid- August the larvae 



