﻿38 BULLETIN" 1351, U. S. DEPAETMENT OF AGRICULTUBE 



ticed by keeping the beds free from dried leaves and applying no 

 mulch. In the spring of 1922, despite a continued and careful 

 search, only a few scattered beetles were found and the greenhouse 

 was practically free from infestation. Undoubtedly the constant 

 hand picking had resulted in a great decrease in the numbers of 

 beetles of the overwintering brood. 



In one instance a modification of the hand-picking method was 

 advised, which resulted in a greater efficiency because of the greatly 

 reduced labor required. It is customary among rose growers to 

 water the plants so heavily every three or four days that the water 

 collects in puddles or pools on the surface of the bed, from which it 

 gradually drains off. Where heavy infestations exist the beetles are 

 dislodged and thrown to the ground during the syringing and water- 

 ing, and on landing in the water they make vigorous efforts to reach 

 the nearest plant or other object on which to make their escape. Va- 

 rious growers took advantage of this habit by haying the gardeners 

 follow the man who watered the plants to collect all floating or 

 swimming beetles possible. In a very short time as many as 1,000 

 beetles were gathered from three beds of roses. 



Although this method of warfare is crude and only partially effec- 

 tive, it appealed to the florists, and for this reason efforts were di- 

 rected toward improving the practice by " filming " the surface of 

 the flood water with a contact insecticide, such as kerosene nicotine 

 oleate.* 



Spraying the insects on the plants with the same solution proved 

 ineff'Sctive, because of their hard wing covers and body. The success 

 of this treatment therefore depended on the beetles swimming 

 through the poison so that it came in direct contact with the softer 

 body parts under the wing covers. Preliminary tests were made 

 with one-half pint of kerosene nicotine oleate stock solution diluted 

 with 4 gallons of water. This solution was applied over about "6 

 square feet of surface by means of a sprinkling can, and the results 

 were promising. Applied in this manner the insecticide was greatly 

 diluted by filming and spreading over the water surface; neverthe- 

 less its effect on the beetles was apparent almost immediately after 

 they carae in contact with it. 



Fourteen beetles were collected and held for observation. Seven of 

 them had been subjected to this treatment, whereas the others had 

 merely been washed from the plants by the force of the water. Two 

 days later the treated specimens were dead and the " checks " were 

 still alive. Three days after the preliminary test 7,000 plants in one 

 large range were treated. Specimens of the treated beetles kept 



8 Kerosene nicotine oleate stock solution is prepared as follows and is a slight modifica- 

 tion of William Moore's original formula. 

 Stock solution : 

 Solution 1 — 



Kerosene 8 parts or 1 gallon. 



Oleic acid 1 part or 1 pint. 



Solution 2 — 



Volatile nicotine 2 parts or 2 pints. 



Water 8 parts or 1 gallon. 



Solution 1 is prepared by slowly pouring the oleic acid into the kerosene, stirring con- 

 stantly. In another vessel solution 2 is made up by adding the volatile nicotine to the 

 water. The stock solution is then prepared by stirring solution 1 into solution 2 and 

 bringing the mixture to a creamy consistency by churning it rapidly for several minutes, 

 pouring from one vessel to the other, or pumping the liquid back upon itself through a 

 bucket pump. 



