Ll. Lloyd 95 



be distended with the bait. As it is necessary to have a moth trap 

 widely open to allow the insects to flutter in it is difficult to prevent 

 their escape by mechanical means, and it was therefore decided to 

 poison the mixture. 



Laboratory tests were made with sodium fluoride, |— 1 per cent.; 

 sodium arsenite, 2 per cent. ; and lead arsenate paste, 2 per cent. ; each 

 mixed with ale and treacle and soaked up in muslin. These were placed 

 in moth cages which included growing tomato plants and newly emerged 

 moths. In the laboratory (T. 64° F.) the moths died off slowly. For 

 example in the case of 1 per cent, sodium fluoride the average life of 20 

 moths was 7-5 days (4-10 days). In the tomato house (T. 70° F.) with 

 the same poison the average life was 2-5 days (1-5 days). The probable 

 explanation of this difference is that at the higher temperature the moths 

 drink more freely. Exposed to 2 per cent, sodium arsenite in the tomato 

 house, five moths had an average life of 3-6 days (1-5 days). 2 per cent, lead 

 arsenate paste was found to be ineffective in the laboratory, eight moths 

 all surviving six days, when the experiment was stopped. This study 

 of moth poisoning was not completed when the number of available 

 moths became too small for its continuance. When sodium fluoride was 

 tested in the laboratory very considerable numbers of eggs were laid by 

 the moths after they had taken the poison, but these were scattered all 

 over the foliage and cage in ones and twos, and not in the normal large 

 batches. One of the jars containing the ale, treacle and sodium fluoride 

 was placed in a moth cage in a tomato house, and 11 newly emerged 

 moths were released in it. All were caught the first night and no eggs 

 were laid. The experiment was repeated with five moths, and four were 

 caught the first night, while the remaining one, a male, was found in the 

 trap on the third day. The moths are thus caught before they have 

 laid any eggs in many cases, and the majority trapped in the houses 

 were fresh specimens which had obviously flown little. However as a 

 few eggs might be laid in the intervals between escape and death, the 

 escape should be prevented as far as possible. The poison prevents 

 fermentation and retards the formation of a scum on the fluid, and the 

 dead bodies should be removed occasionally so that they do not form a 

 platform. 



Sodium fluoride is not a perfect poison and further search for a more 

 effective one will be made. It has the advantage that it is not at all 

 dangerous in use, and its employment in the greenhouses will ensure 

 the early death of any moths which feed and escape from the jars. 



Wholesale moth trapping was carried out in a block of 12 200-foot 



