Sept., '02] ENTOMOLOGICAL NEWS. 22Q 



Constantia. The thorough drenching of the trees within three 

 days after spraying apparently had no injurious effect. 



In Bulletin No. 30, new series, Division of Entomology, U. S. 

 Department of Agriculture, Mr. C. L. Marlatt records an inter- 

 esting test with lime-sulphur-salt wash, but reports no definite 

 observations after the first heavy rain. It would have been 

 very interesting had the observations been continued several 

 months longer so as to note the effect on the young scales as 

 they emerged. Judging from Mr. Marlatt's statement that 

 "the infested trees, especially those that had been pruned 

 back, made a very vigorous growth, and the fruiting and 

 growth of the others were entirely satisfactory," the young 

 scales were probably destroyed as well, for, if Diaspis penta- 

 gona Targ. increases in the latitude of Washington as rapidly 

 as it does here at the Cape, with 50 per cent, or more of the 

 scales on the young wood alive, the trees would certainly be 

 badly infested before the next dormant period. 



Other similarly infected trees were sprayed at the same time 

 with kerosene emulsion in varying strengths up to one part 

 emulsion to two parts water, but the results were uniformly 

 unsatisfactory. With whale oil soap at the rate of two pounds 

 per imperial gallon, the destruction of the scale was apparently 

 complete without injuring the tree. Weaker strengths, from 

 one-quarter to one pound per imperial gallon, were not effectual 

 in destroying the old scales, but the after effect on the young 

 was similar, though not so marked, to that of the lime-sulphur- 

 salt wash and the sheep dip. A similar after effect has been 

 noticed in treating pear and citrous trees with soft soap, one 

 pound to three imperial gallons of \vater, for the destruction 

 of Aspidiotus aurantii Maskell, the old scales succumbing after 

 a time, leaving the trees quite free. 



The observations up to January 4, 1902, indicate : 



1 . Under South African conditions, neither lime-sulphur-salt 

 wash nor lime-sulphur sheep dip have any marked insecticidal 

 value for Diaspis pentagona Targ. after the scale is complete. 



2. The young are destroyed soon after emerging, even though 

 three months or more may have elapsed since the application. 



3. Lime-sulphur wash, as represented by the lime-sulphur 



