NO. 10 TROPISMS OF LEriDOPTERA — McINDOO 9 



was probably perceived by oriental fruit moths and they were probably 

 attracted by it. Codling moths seemed to be more strongly photoposi- 

 tive to blue and violet lights than were oriental fruit moths. The 

 responses of males and females of both species to colored lights ap- 

 peared to be similar. Experiments in which ordinary electric lights 

 were installed in a peach orchard were unsuccessful, only a few of 

 the oriental fruit moths being caught in traps. Codling moths were 

 not tested in orchards. 



There is considerable difiference of opinion regarding the apparatus 

 to be used in light experiments. Yerkes and Watson (91, p. 3) say 

 that simpler and more conveniently manipulated apparatus may be 

 used in preliminary work, but emphatically recommend that such 

 apparatus be abandoned as soon as possible. They recommend a very 

 complicated piece of apparatus for thoroughgoing, intensive, and 

 quantitative work. 



(g) Light traps are not yet considered successful. — Dewitz (9) in 

 1912 briefly discussed the practical side of phototaxis as applied in 

 economic entomology, but regretted that this subject had never been 

 seriously studied from a scientific point of view. To his knowledge 

 only one investigator spectroscopically examined the various lights 

 used. This man projected a large spectrum on a screen in a dark room 

 and then observed certain moths collect on the different colors of the 

 spectrum. He found that the less refractive colors (red to green) 

 exercised by far the strongest attraction. It is also stated that experi- 

 ments were conducted in vineyards in Germany in which lamps pro- 

 vided with glass covers of various colors were used. The lamps with 

 green glass attracted the largest number of moths. 



According to Dewitz, artificial light as a control measure was first 

 used in 1787 for attracting vine moths to lighted candles on window 

 sills and to wood fires in vineyards. Since that date light traps have 

 been gradually developed and improved until to-day there are many 

 types and varieties of kerosene, acetylene, and electric lamps used for 

 this purpose. It seems that none, however, has given complete satis- 

 faction as a control measure. The present writer does not know of a 

 single authentic report that this method has been successful on a large 

 scale, although he has a recent newspaper report stating that along 

 the German-Polish frontier powerful searchlight traps have been used 

 successfully against a nocturnal moth whose larvae ravage the pine 

 forests. Millions of moths are said to have been cremated by being 

 attracted to flames near the searchlights. 



