lO 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



At last an investigation on a large scale, in which up-to-date scientific 

 methods are being used, has been started l)y the New York (Geneva) 

 State Agricultural Experiment Station and the Empire State Gas and 

 Electric Association. So far only a progress report of this work has 

 been presented by Parrott (/O), who regards a study of tropic re- 

 sponses of insects as one of the most promising fields of entomological 

 inquiry, and who believes that when the more important facts about 

 light attraction for insects are known we may, perhaps, be able to 

 change some of our present practices on insect control. Experiments 

 in orchards in which various kinds and colors of electric light bulbs 

 were used gave a total catch of 65,000 insects, of which 29.6 per cent 

 were Lepidoptera and 52.5 per cent were Diptera. All of the Lepi- 

 doptera, most of the Coleoptera and Hemiptera, and a smaller per- 

 centage of the Diptera and Hymenoptera caught were injurious 

 species. Among the Lepidoptera were the codling moth, fruit-tree 

 leaf-roller, cutworm moths, and several other species. This method 

 was also found useful for trapping codling moths and other injurious 

 insects in cold storage houses. In a dairy barn clear and white frosted 

 bulbs attracted more flies than did the other colors, and red attracted 

 the least of all. Tests in which colored glass filters were used with 

 several species of moths including codling moths and European corn- 

 borer moths showed that these insects did not respond to the red end 

 of the visible spectrum, but the light yellow, light blue-green or day- 

 light, red-purple, and blue-purple filters proved the most attractive. 



2. PHOTOTACTIC EXPERIMENTS ON CODLING-MOTH LARVAE 



The writer, like other observers, has found the adult codling moth 

 an unfavorable insect on which to experiment in the laboratory. These 

 moths are extremely erratic in behavior. They are very quiet and 

 usually non-responsive during the daytime, but at dusk and later they 

 are more active and readily respond the first time, although thereafter 

 their responses are irregular and not fully reliable. Since the same 

 individuals cannot be repeatedly tested with satisfaction and as the 

 writer's supply of them was limited, he was not able to conduct the 

 experiments as originallv planned. 



Having failed to obtain definite results by testing a small number 

 of the adults, the writer spent much time in 1927 on the larvae, 

 which proved to be more favorable material for tropic tests. In all 

 154 larvae, belonging to the two broods at Silver Spring, Md., were 

 tested in the laboratory under various conditions. Most of them 

 had been reared from eggs in the laboratory. The wormy apples 



