115 



In previous articles [see above] the author reported the good results 

 obtained during the first two years in which saving the trash and 

 ploughing it under v/as tried. During those years it was always easy 

 to find the parasites of D. saccliaralis during the summer, but in 1915 

 they were very scarce, and when the counts were made to determine 

 the percenta.ge of infestation in the burnt and unburnt fields, it was 

 found that all were about equally infested by the borer. It is believed 

 that this result was caused by the long period of dry weather during 

 the summer, the drought lasting in different places from 60 to 120 

 days. In Porto Rico, Wolcott has found that infestation by the 

 borer varies inversely with the rainfall, the less the rainfall, the greater 

 the number of infested canes [see this Review, Ser. A, iii, p. 760]. 

 One reason for this may be that dry weather is unfavourable to the 

 parasite, Trichogramma oniuutum. During 1915, experiments in 

 importing beneficial insects from the cane-fields of Cuba have been 

 of such a character as to justify further work in that direction ; it is 

 very improbable that the same weather would have a similar effect 

 on every beneficial insect. A third means of control is furnished by 

 applications of lead arsenate ; by covering the plants with a poison 

 in powdered form, a poisoned leaf surface is presented to the first 

 young borers and the greater number of dead hearts are thus prevented. 

 Two applications of powdered lead arsenate were made on a plot of 

 cane in the spring of 1915, the powder being shaken on to the young 

 plants from a cheese-cloth bag by hand. When the cane was cut in 

 December, the infestation of stalks was only 5 per cent, in the poisoned 

 plot, while that in the control plot was 24 per cent. The former amount 

 of infestation is of little consequence and the cost of this treatment 

 is small. These experiments will be continued on a larger scale. 



HousER (J. S.). Recent tests of materials for controlling San Jos6 

 scale. — Mthhj. Bull. Ohio Agric. Expt. Sta., Woosler, i, no. 1, 

 January 1916, pp. 21-27, 2 figs. 



Since it was first obsened in Ohio twenty-one years ago, the San 

 Jose scale [Aspidiotus perniciosus] has spread throughout that State apd 

 in many places fruit trees have been practically exterminated, largely 

 owing to this pest. Up to the present, the Entomological Depart- 

 ment of the Station has answered 1,399 letters definitely referring 

 to it. The home-boiled, dilute lime-sulphur wash ; the connnercial, 

 concentrated lime-sulphur wash (1 part to 7 parts of water) ; and the 

 soluble oils (usually 1 part to 15 parts of water) are standard remedies 

 which will control the scale if properly applied. The concentrated 

 lime-sulphur has a tendency to leak through the containers and only 

 an exceptionally well-made barrel or keg will prevent this liquid from 

 escaping. The test results obtained with powdered lime-sulphur 

 compounds were promising, and should further trials prove their 

 efficiency, it seems likely that these will supplant the concentrated 

 liquid sprays as scale remedies, provided that they can be sold at a 

 reasonable figure. Most failures to control this scale are traceable to 

 the fact that only about one-fourth or one-third of the necessary 

 amount of spraying material is used. Trees, especially large ones, 

 should be sprayed from three or four sides, using favouring winds. 



