SECTION X.— METHODS OF CONTROL. 14"> 



in Trinidad at Brechin Castle in September 1917 1 tested the same 

 acetylene lamp and on one night obtained '2,170 insects as compared 

 with 1,008 with an oil lamp some distance away ; and on the next night 

 it captured 1,132 when two oil lamps one on each side captured an 

 average of 1,110. 



It appears that there is no great increase of captures by using lights 

 of greater intensity and the percentage of females captured remains the 

 same. 



Colour of Lights. To test if lights of different colours were more 

 attractive to females I put out oil lamps with white, green and red 

 sliades at Brechin Castle Estate in September 1917. 



The results were as follows : — 



Colour. Average Catch. Per cent, uf Females. 



White 1,228 about 1 per cent, 



lied 146 



Green 443 „ 



It will be seen that the percentage of females is not increased while 

 the total attractiveness is reduced, more so in the case of the red than 

 the green. 



Height and Fosition of Lamps. To test the best height at which to 

 place the lamps and whether they are best in the canes or in the traces, 

 experiments were carried out at Golconda Estate in September 1918. 



The lamps were tested (1) on the ground, (2) about 18 inches froui 

 the ground, (3) about four feet from the ground. 



The results obtained were as follows :— 



1st Night. 



Li trace Iii canes Total 



High 30 220 250 



Medium 166 446 612 



Total 531 1,317 1,848 in 6 lamps 



It will be seen that in all cases the lamps at 18 inches above the 

 ground are much more efficient than tliose at four feet, while the total 

 captures at ground level were greater than those at IH inches, although 

 the results are less conclusive as in one case the total was lower for the 

 lamp on the ground. 



With regard to the position it appears that the lamps in the canes 

 c.iught many more than those in the traces, but the canes liad suffered 

 severely from froghoppers and were small and oi)cn while the traces 

 had ploughed land at one side. 



Time of Greatest Captures. On p. 57 and in tig. 8 is sliown 

 the numbers of froghoppers caught during each hcwr of the night. It 

 will be seen that the greatest number are caught during the early part 

 of the night and more than fifty per cent, of the total are attracted 

 bi tore 10 p.m. 



