77 



presence of its enemy. It is only in the larval stage that P. berlesei 

 attacks the scale, and only one individual is affected. Both the larvae 

 and adults of predatory insects, such as Chilocorus hifustulatus and 

 Rhizobius lophantae, destroy large numbers of scales, though their work 

 is not so apparent, as the scales are not left attached as in cases of 

 parasitism by P. berlesei. These Coccinellids must be considered of 

 prime importance in the control of A. pentagona and in no way injurious 

 to P. berlesei. 



Les traitements k I'eau chaude. [Hot water treatment.] — Rev. Vitic, 

 Paris, xliii, no. 1118, 2nd December 1915. 



I. Semichon (L.). Traitement des vignes en v6g6tation par I'eau 

 chaude. [The treatment of vines in active growth with hot 

 water.] pp. 413-414. 



Differences in equipment and in the method of operating account 

 for the divergent results obtained by M. Chauvigne [see this Review, 

 8er. A, iii, p. 562] and by the author. The latter used a Vermorel 

 sprayer with a hand pump and a nozzle projecting a coarse spray. 

 The temperature of the liquid at varying distances up to 20 inches is 

 shown by a carve in a diagram illustrating this article. A second 

 curve shows the rapid drop in temperature which occurred when a 

 fine nozzle was used, and a third curve indicates the still greater loss 

 of heat when high pressure was used. In the first case the temperatures 

 were those obtained by the author ; in increasing the distance from 

 4 to 20 inches the temperature was reduced from 158° F. to 139° F. 

 With the fine nozzle, the temperature was reduced from 153° F. to 

 131° F. With a pressure sprayer, the respective temperatures were 

 122° F. and 101° F. In all three cases the water in the tank was at 

 1G2° F., so that in the last case the drop was very marked immediately 

 the spray left the nozzle— at 5- inches the temperature had already 

 fallen to 139° F. and at 2 inches it was only 131° F. The causes are 

 twofold : firstly, the finer particles cool more rapidly and secondly 

 the sudden release from pressure cools the liquid. Spraying with 

 hot solutions must therefore not be done with pressure sprayers or at 

 too great a distance. The wetting power conferred by heat compen- 

 sates for the loss of wetting power due to the coarse spray. 



II. Chauvigne (A.). Th6orie de la d6croissance du degr§ de chaleur 

 des pulverisations chaudes. [The theory of the decrease in the 

 degree of heat of hot sprays.] pp. 415-417. 



The data arrived at are based on (1) a tank temperature of 160° F. 

 at the beginning of operations, (2) the use of a Vermorel sprayer, 

 throwing a fine jet, (3) a surrounding temperature of 65° F., and 

 (4) a distance of 20 inches between the nozzle and the plant. The 

 initial temperature of 160° F. dropped to 151° at 4 inches, to 132° at 

 8 inches, to 118° at 12 inches, to 110° at 16 inches and 103° at 20 inches. 

 The fall is most marked in the first eight inches. When the contents 

 of the tank were heated to 212° F. a temperature of 117° F. was 

 obtained at the 20 inch limit. As a temperature of 139° F. or 150° F. 

 is required against insect pests of the vine, the hot water treatment 

 is considered useless. The reasons for the loss of heat are discussed. 



