ELECTRIC STATE OF THE ATMOSPHERE. Moths are apparently stimulated to 

 flight in thunderstorm weather, but it is difficult to disentangle any effects of atmospheric 

 electricity from other influences. Heavy catches often precede storms. 



CLOUDINESS. A cloudy night is usually a good night for moth trapping. Of course, 

 the presence of clouds cuts out moonlight, if it would be present, and holds in the warm 

 air against radiation, thus making conditions favorable. In the absence of useful data, 

 the writer would say that a cloudy night is favorable for photosensitivity because tempera- 

 ture and humidity are liable to be high. 



LUNAR PERIODICITY. Stirrett (1938) seemed to find very little correlation between 

 lunar periodicity and flight of the corn borer. However, anyone who has used light traps 

 found to his sorrow that the presence of a full moon will greatly reduce his captures. 

 This is so marked that it has become quite usual to cease trapping operations for a few 

 days around full moon. Dirks (1937) in his studies of the trapping of moths in Maine 

 presented a table showing strongly the effect of moonlight on his catches. 



In an attempt to obtain some quantitative data, some of the same index catches used 

 for correlation with temperature changes above were tabulated with respect to their rela- 

 tion to full moon and new moon, respectively. The date of the moon's change was taken as 

 zero, and the catches 1 and 2 days before and 1 and 2 days after the change tabulated. 

 Since this took only 10 days out of the month, and the trap was not run on many nights 

 around full moon, about 15 to 20 instances were obtained for each day. When the catches 

 were averaged, it was found that those around the new moon ran between 92 and 117 per- 

 cent of the normal catch, but those for full moon and the preceding night were 77 and 71 

 percent, respectively. The full moon rises at sunset, and comes up about an hour later 

 each evening. Thus, the 77 percent catch the night of full moon rises to 102 the following 

 night, and stays around 100 for the next two nights. The catches before full moon reflect 

 the presence of the moon during early evening. 



GOOD NIGHTS AND POOR NIGHTS. All operators of light traps have noticed this 

 variation, which is often not subject to explanation. Williams stated that good nights were 

 those in which the moths started flying soon after sunset and continued to fly throughout 

 the greater part of the night. On poor nights the flight started at a lower level and fell off 

 rather rapidly. 



FOG OR MIST. Stirrett gives the only information I could find on these points. Fogs 

 were very infrequent during his period of study, but he concluded that they had little 

 influence on the flight of moths. This does not mean, however, that light trap catches 

 might not be affected, as fog would reduce the distance from which the trap would be 

 visible, and cut down its effectiveness to that extent. 



DEW AND GUTTATION. Stirrett found no relation of these factors to moth flight. 



RELATIONSHIP OF PHYSIOLOGICAL DEVELOPMENT AND 

 CONDITION OF INSECTS TO PHOTOSENSITIVITY 



H. Tashiro ' 



Literature is replete with studies on the photosensitivity of insects, but rather limited 

 and fragmentary as it relates directly to the physiological development or condition of 

 insects. Much of it is only indirectly related to this specific topic. 



i Entomologist, Entomology Research Division, Agricultural Research Service, U. S. D. A., Geneva, N. Y. 



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