61 



(cabbage butterfly) ; Plutella maculipennis, Curt, (diamond-back 

 moth) ; Ceramica picta, Harr. (zebra caterpillar) ; Aphis brassicae, L. 

 (cabbage aphis) ; Thrips tabaci, Lind. (onion thrips) ; Phytometra 

 {Autographa) brassicae, Riley ; Evergestis straminalis, Hbn. (purple- 

 Isacked cabbage worm) ; and blister beetles, such as Epicauta penn- 

 sylvanica, De G. (black blister beetle), E. cinerea, Forst. (grey blister 

 beetle), and Macrobasis unicolor, Kirby (ash-grey blister beetle). 



The locusts occurring in the Province include Melanoplus athntis, 

 Riley (lesser migratory), M. femvr-rubrum, De G. (red-legged), 

 Camnida peUucida, Scudd. (pellucid), and Melanoplus bivittatus, Say 

 (two-striped). 



The usual controls are given for these pests and several formulae 

 for insecticides are included. 



Leopold (— ). What Insecticides and Fungicides shall we use in 1917, 

 and when shall we spray this Year ? — Ninth Ann. Rept. Quebec 

 Soc. Protection Plants from Insects & Frmgoiis Dis., 1916-1917 ; 

 Quebec, 1917, pp. 42-44. [Received 12th December 1917.] 



Various spraying mixtures have been adopted in turn, as each was 

 found more efficacious than the last. Arsenate of lead paste, which 

 has long been in favour, is now being replaced in many cases by the 

 powder, and the author questions whether a cheaper and just as 

 effective insecticide as arsenate of lead could not be found. He is 

 convinced also that the dormant spray for apple scab can be omitted 

 without loss to the crop. Arsenate of lime is suggested as a possible 

 substitute for arsenate of lead in all lime and sulphur sprays and with 

 Bordeaux mixture ; the arsenic in the former substance costing less 

 than 55 per cent, of what it does when in the form of arsenate of lead. 

 Arsenate of lime is known to do less damage than arsenate of lead 

 with an equal strength of lime-sulphur. When arsenate of lead is 

 added to hme-sulphur solution, a chemical change takes place, 

 resulting in the formation of lead sulphide and three kinds of arsenate 

 of lime, one of which, the mono-calcic-arsenate, is highly soluble and 

 causes a large part of the scorching that results from the use of lead 

 arsenate and lime-sulphur together, while nearly all the lead goes to 

 the bottom of the tank as lead sulphide. AVhen arsenate of lime is 

 added to lime-sulphur, no chemical change takes place and so no soluble 

 arsenic is formed. Arsenate of lime is therefore safer than arsenate of 

 lead with a lime-sulphur spray, but it should never be used alone. 

 Arsenate of lead on the other hand may safely be used alone. 



The efficacy of Bordeaux mixture in preventing the falling of apples 

 from the tree is questioned ; and the results of experiments to determine 

 at what period the lime and sulphur cause most scorching and dropping 

 of the apples show that the greatest damage occurs two weeks or more 

 after the blossoms, while Bordeaux mixture, used two weeks after the 

 blossoms, is harmless as regards falling of the fruit. In suggesting a 

 new scheme of spraying, which has been made as economical as possible, 

 the author quotes Sander's work and gives substantially the same 

 recommendations as those already published [see this Review, Ser. A, 

 V, p. 230]. 



