THE EOSE APHIS. 13 



On April 23, at a Virginia station near Washington, a number of 

 large rosebushes trained on the side of a house and well infested with 

 aphides were sprayed. Both winged and wingless forms of aphides 

 were present. Nicotine sulphate was applied, with and without the 

 use of soap as in the previous formula, at the rate of 1 part to 1,000 

 of water. In the experiments without the use of soap some diffi- 

 culty was found in obtaining a spreading action of the spray, and con- 

 sequently only about 90 per cent of the aphides were reached. It is 

 believed that all reached by the spray were killed. When nicotine 

 sulphate was used at the rate of 1 part to 1,400 parts of water 

 and 1 part to 1,500 parts of water, results were not satisfactory, only 

 about 25 and 10 per cent, respectively, being destroyed. With the 

 use of soap 100 per cent of the aphides on the vines were killed, the 

 results being very satisfactory. At the rate of 1 part of nicotine 

 sulphate to 1,400 of water with a laundry soap added, 90 per cent of 

 the aphides were killed; whereas the results with nicotine sulphate 

 at 1 part to 1,600 of water and 1 part to 1,800 of water in combination 

 with soap were unsatisfactory, only 70 per cent and 50 per cent being 

 killed. 



In these experiments a compressed-air sprayer with Bordeaux type 

 of nozzle was used at an estimated pressure of 90 pounds, and a fine 

 but driving spray was employed. The water used for the dilution of 

 the insecticide was particularly soft, but contained a very small 

 proportion of sulphur. 



From these experiments it may be concluded that nicotine sulphate 

 at the higher dilutions as used in these experiments is much more 

 effective against the rose aphis when used in combination with whale- 

 oil or other soaps, since the spreading action thus induced is much 

 more favorable. The plants may, however, be injured in case the 

 spray solution is too strong. It is not believed that the injury shown 

 in the experiments was caused by nicotine sulphate used at too great 

 a strength, since it has been applied experimentally to roses in the 

 greenhouse at the rate of 1 part nicotine sulphate to 15 parts of water 

 without injury other than the appearance of mildew, undoubtedly 

 superinduced by the spraying. It is apparent from the results 

 obtained that a spray can not be employed weaker than 1 part of 40 

 per cent nicotine sulphate to 1,400 parts of water with satisfactory 

 results unless in combination with whale-oil or other soap. 



ARTIFICIAL CONTROL IN THE GARDEN. 



Experiments have been conducted against the rose aphis with 

 different nicotine extracts under different conditions as to strength 

 and weather. In no case, in the writer's experience, were the plants 

 injured, whereas the insect was destroyed in enormous numbers. 

 The aphis is easily controlled by spraying with nicotine solutions 



