REACTIONS TO LIGHT 165 



catches of moths have been recorded by Neustadt (1913), usmg 

 incandescent lamps containing mercury vapour, in which these 

 component rays were well represented. 



More or less detailed analyses with respect to the species of 

 Lepidoptera attracted to light traps, the proportions of the sexes 

 represented and other data will be found in publications by 

 Willcocks (1916), Criddle (1918), Ainslie (1917), Shiraki (1917), 

 Turner (1918, 1920), Ballard (1923), Theobald (1926), Husain and 

 Khan (1934), and others. For the most part the results recorded 

 by these observers are not encouraging, but in some cases the 

 experiments were far too inadequate to be conclusive. Shiraki, 

 however, has obtained promising results from the use of light 

 traps with reference to the paddy borer moth {Schoenobius 

 incertellus) in Formosa. He records five years' observations, and 

 during this period many thousands ot individuals were captured 

 by the method in different localities. In practically all cases his 

 figures show a great preponderance of females, although at the 

 time of the commencement of the emergence of each generation 

 of moths, more males than females responded. Shiraki's observa- 

 tions are supported by those of Ballard (1923) in India, who 

 likewise demonstrated that an enormously greater number of 

 female moths of this species, as compared with males, are caught 

 by means of light traps. He also showed that out of 13,640 

 trapped females, 35-5 per cent, had previously laid their eggs 

 before being caught. Theobald (1926) has recorded the results of 

 two years' experiments in England, and concluded that acetylene 

 lamps are beneficial in destroying Tortrices in orchard districts 

 where these pests are serious. Unlike some observers, he fcund 

 that no objection could be raised against light traps on the grounds 

 that large numbers of beneficial insects were destroyed at the 

 same time. 



Husain and Khan (1934) carried out investigations with light 

 traps in the Punjab with reference to the Pink Bollworm Moth 

 (Platyedra gossypiella), which is a well-known pest of cotton. After 

 enumerating certain disadvantages attendant upon the use of 

 this method, they concluded that a light trap, instead of minimising 

 attacks in the field where the trap was stationed, only concentrated 



