Ll. Lloyd 93 



they were put on they were all dead. Ten more half-grown larvae were 

 then placed on another leaf, and ten days later these were all dead. The 

 spray therefore remained potent for 20 days. The foliage of the plant 

 was not damaged and the fruit set normally. This plant at the end of 

 the experiment was photographed with a control plant of the same age 

 which, without spraying, was infested with 10 half-grown larvae at the 

 time the second lot were released on the sprayed plant. They completely 

 ate a leaf each day and had destroyed the plant by the time those on the 

 protected one were all dead (see PI. IX, fig. 4). Similar experiments were 

 carried out with strengths of 5, 2|, If, 1| and f lbs. of the alcoholic 

 extract in 100 gallons of water respectively, and each plant was infested 

 with 22 larvae as described above. The results varied little from those 

 detailed, except that with the weakest strength the death-rate was 

 somewhat slower. None of the plants were damaged and the substance 

 therefore appears to be safe to use, but no large scale experiments were 

 carried out. At present there are no supplies of this substance available 

 in England. Should it become available in large quantities it will prove 

 a very useful adjunct to the arsenate of lead for later spraying. When 

 the foliage of the plants becomes dense however treatment becomes 

 more difficult, and will prove less effective in consequence. 



(ii) Larva Trapping. 



When spraying is not practicable the infestation may be reduced by 

 trapping the mature larvae by means of sacks. They travel considerable 

 distances in seeking suitable places in which to pupate, and sacking 

 proves very attractive to them. Sacks placed about the houses will 

 therefore catch a surprising number. They should be loosely folded and 

 placed on the pipes under the gutters, or on the lower wires and touching 

 the woodwork. Naturally the more used the better, but four or five to 

 a house will collect hundreds of pupae in a moderately infested block. 

 A count of them in 11 sacks, distributed in three houses and left for 

 three weeks in September, gave a total of 729, or 66 to a sack (see PI. X, 

 fig. 5). 



It is a long and tedious business to remove the larvae and pupae 

 from them by hand, and it will be found more economical and thorough 

 to collect them in a barrow and to dip them for half-a-minute into a 

 cauldron of boiling water, and then to shake them. This will kill all 

 the pupae, and also the wireworm beetles and the vast swarms of wood- 

 lice which also find sacking attractive. They should be collected and 

 dipped every 21st day. If they are left longer moths may begin to emerge. 



