Below 60° few moths were taken. With favorable temperatures few moths were captured 

 when the wind velocity was 10 m.p.h. or more, but at 6 m.p.h. many were captured. It 

 appears quite evident that low catches during periods of unfavorable meterological 

 conditions are the result of inhibited insect activity rather than an influence on photo- 

 sensitivity. 



Period of night and response to induced light . Considerable variation is apparent in 

 this regard. In Mississippi (15) it was concluded that the time between 1 a.m. and 3 a.m. 

 was the turning point for activity of all major insect groups in their response to light 

 traps. Response of corn borer to light traps in Indiana (9) began at dusk, maximum flight 

 reached between 11 p„m. and 2 a.m., and dropped off rapidly after 2 a. m. Pink bollworm 

 moths (13) responded to blacklight in greatest numbers between 2 and 4 a.m. Observations 

 on the European chafer in 1958 and 59 revealed another pattern of response to black- 

 light. Greatest response occurred before midnight, with a lull in activity during the middle 

 of the night, and a secondary peak of activity after 3 a.m. 



Sexual response to induced light. It has long been surmised that males were stimulated 

 more than females to light stimulus. This belief, it is stated, was found in general to be 

 erroneous and that both sexes are apparently equally responsive. When only 1 sex is taken 

 it generally indicates sexual difference in time and place. Females usually fly only after 

 mating, but males fly constantly in search for females. Males are said to fly higher than 

 females (11). Results often do not bear out these generalities. In trapping mixed popula- 

 tions of 28 species of noctuid moths throughout the night male catches increased through 

 the night while that of the females remained quite constant. Males increased from 52 

 percent during 7 to 9 p.m. to 81 percent during 3 to 5 a.m. Most females were caught in 

 a trap 16 feet high and most males at 4 feet (7). The sexual response of pink bollworm 

 moths to light traps was observed during 3 successive years in Texas. The field popula- 

 tion is considered to have a sex ratio of 1:1. In 1952, 70 to 75 percent of the moths cap- 

 tured were males (13), in 1953, 74 percent of total catches were males (18), and in 1954 

 the vertical position of blacklight did not influence the preponderance of males (14). From 

 55 to 72 percent of all codling moths captured in light traps in New York, Pennsylvania, 

 Indiana, and California (5) were males. A 3-year study of hornworm moths in tobacco 

 fields caught in blacklight traps was made. Of the total tobacco hornworms, 82 percent 

 were males, but only 54 percent of the tomato hornworms were males (21). Sexual response 

 of stable flies was influenced by intensity. At wavelengths of 3650 to 4900 A. and low 

 intensities, males responded more readily than females, but at higher intensities the 

 males were less responsive than females (1). 



A few figures are available for Coleoptera. The members of the genus Phyllophaga 

 are reported (2) to show no significant sex preference for any of the colored lights to 

 which they are exposed. Field populations of the European chafer have a male to female 

 ratio of approximately 2:1. In 1958, 62 percent of all the beetles captured in blacklight 

 traps were females. During 1959 the trend was the same with 53 percent of all beetles 

 captured in blacklight traps being females. Neither period of season, location, or period 

 of night influenced the sexual response of the beetles to blacklight. 



Position of lights and insect response . The vertical position of blacklight traps and 

 response of pink bollworm moths were studied by placing traps at 2-foot intervals from 

 2 to 14 feet (14). There was a progressive decrease in moths captured from the lowest 

 position with 39 percent to the highest position with only 6 percent of the total captured. 

 In a mixed population of moths (7) blacklight traps placed at 16-foot elevation caught 

 equally as many moths as did the one placed at the 4-foot level. Traps at the 8- and 12- 

 foot level caught equally low numbers. The position of the blacklight trap in relation to the 

 position of the European chafer was of considerable importance. In the evening the 

 beetles emerged from the ground and flew into nearby trees without paying any attention 

 to the light traps. After coming to rest in the trees they were attracted to the lights. In 

 1959 it was determined that the position of the trap in relation to the tree on which beetles 

 congregated was of prime importance. More beetles were captured in traps directly 

 under the tree or at its periphery than traps out in the open. 



41 



