SUMMARY OF RESULTS. 31 



gram per cubic foot and with exposures of one hour, three hours, and 

 overnight, all scales were uniformly killed. The holding of fruit in 

 a warm room for a couple of days previous to examination resulted 

 in a marked discoloration of the dead insects, leaving no doubt as 

 to their condition. 



Variety-of-fruit series {Table VI). — Numerous varieties of apples, 

 including the principal commercial sorts, fumigated for one hour and 

 using potassium cyanid at the rate of 0.30 and 0.50 gram per cubic 

 foot, were not in any way injured. 



Rhode- Island-Greening-injury series ( Table VII) . — The only variety 

 of apple used in the tests showing gas injury was the Rhode Island 

 Greening from western New York. Other fruit of this variety of 

 unknown source was not injured by an excessive strength of the gas. 

 No strength of gas or period of exposures was determined which was 

 not injurious to western New York Greenings. Injury was more 

 pronounced on fruit subjected to a long exposure than when a heavier 

 dose and shorter exposure were given. 



Fumigation of dry, moist, and wet fruit (Table VIII). — Observations 

 made at different times on fruit fumigated in a dry, moist, and wet 

 condition showed that its condition in this respect was immaterial. 

 Apples thoroughly wet by applying water with a spray pump were 

 not in the least injured, and all scales were killed. 



Cold-storage series ( Table IX) . — Fumigation of scale-infested apples 

 in a local cold-storage plant with the temperature 30° F. showed that 

 adequate diffusion of the gas occurred, killing all of the scale insects, 

 and without injury to the fruit. 



Mortality of scales on fruit during winter (Tables II and XI). — Data 

 obtained at different times on condition of scales on untreated fruit 

 for comparison with their condition on fumigated fruit showed, as 

 occurs normally out of doors, that the very young and old scales die, 

 the survivors being mostly those about one-third grown. In the case 

 of fruit held in storage in 1907-8, until March 3, only about 9.5 per 

 cent of scales present were alive, and these were exclusively about 

 one-third grown. In 1906-7 the percentage of live scales present on 

 Baldwin apples, on the 12th of November, 55.90, dropped by Decem- 

 ber 3 to 30.20, and on the Rhode Island Greening variety, from 

 30.20 per cent alive on same date to one-tenth of 1 per cent alive by 

 February 27 — practical extermination. 



Carbon-bisulpJiid series (Table X). — Treatment of scale-infested 

 fruits with carbon bisulphid at strengths varying from 0.069 to 1.81 

 cubic centimeters per cubic foot and for a period of three hours failed 

 to kill the scales to any extent. No injury resulted to the varieties 

 of fruit used, namely, Baldwin and Rhode Island Greening. 



