LEPIDOPTERA AT LIGHT TRAPS 



By W. B. Turner, Scientific Assistant, Cereal and Forage Insect Investigations, Bureau 

 of Entomology, United States Department of Agriculture 



INTRODUCTION 



In the summer of 191 6 extensive observations were made at the 

 Hagerstown (Md.) field station of the Bureau of Entomology for the 

 purpose of obtaining additional information concerning the relative 

 proportions of the sexes of moths taken at light traps. The results of 

 these observations have been stated in a paper recently published.* 



While the observations of 191 6 were being carried on, it was hoped 

 that opportunity would be found in the summer of 191 7 for securing 

 more minute data as to the night-flying habits of Lepidoptera, Various 

 circumstances contributed to the defeat of the project in 191 7, and in 

 the summer of 191 8 it was conducted under conditions even more 

 restricted than in 191 6. 



It was impossible to devote every night to the work, and the com- 

 promise schedule of two nights each week was unavoidably interrupted 

 by the absence of the writer on field duty and by the moving of the 

 laboratory. 



The work was carried on during the period from May 14 to September 

 13, so the proposed schedule of two nights each week would have embraced 

 36 observations. On account of the interruptions mentioned, only 28 

 nights were given to the work. 



DESCRIPTION OF TRAP 



The attracting light, with accessory cone of tin, was described in the 

 paper to which reference has been made. The trap devised by the 

 writer is illustrated in figure i. 



The trap was 12 by 14 inches at the base and 20 inches high, con- 

 structed of heavy galvanized iron. An opening 9 by 10 inches afforded 

 access to the interior and was closed by a door 10 by 11 inches, the 

 overlapping half inch on each margin being covered by strips of heavy 

 felt cemented to the trap, so that the door was practically air-tight. 

 The galvanized iron thimble supporting the glass tube which conveyed 

 the acid to the cyanid was lined with felt, and the opening in the top 

 to receive the cone was provided with a felt gasket. A ball of absorbent 

 cotton tied in muslin and dropped into the cone further retarded the 

 escape of the hydrocyanic-acid gas. A glass vessel with rounded bottom 



' Turner, W. B. female lepidoptera at light traps. In Jour. Agr. Research, v. 14, no. 3,'p. 135-149. 

 1918. Literature cited, p. 148-149. 



Journal of Agricultural Research, Vol. XVIII, No. 9 



Washington, D. C. Feb. 2, 1920 



tn Key No. K-Sa 



(475) 



