304 



Journal of Agricultural Research 



Vol. XXII, No. 6 



Table V. — Number of Porosagrotis orthogonia moths caught at trap lights at Willow 

 Creek, Mont., during the season oj igzo 



Aug. 



Sept. 



13 

 14 

 IS 

 16 



17 

 18 



19 



22 



23 

 24 



25 



26 



27 

 28 

 29 

 30 

 31 



Weather conditions and remarks. 



Number 

 of moths 

 caught. 



127 



342 



1,528 



1,566 



449 



68 



11,720 



Rain in afternoon; night warm, cooler toward midnight 



Early part of night warmer than usual; warm after midnight. . . 



Warm all night 



Night moderately warm 



Cooler, especially so after 9.30 p. m. ; not as many moths flying . 

 High wind in afternoon blew over traps; cold and windy after 



dark ; no moths out 



Windy; cold soon after dark, almost frost; moths flew only a 



few minutes 



Warm at 8 p. m.; moths flying heavily; windy and cooler after 



ir.30; fewer moths out 



Warm west wind most of night; heavy flight of moths 13 , 990 



Same as night before; height of flight 9.15 p. m 14.950 



Warm, light west wind 13 , 650 



Warm, west wind; wind strong and cold after 12.30 a. m 16,250 



Cold and cloudy after 9 p. m. ; southwest wind ! 7 , 490 



Windy and cold ; moonlight; no moths flying ' 



Windy until 8 p. m.; clear, cold; full moon; no moths flying. 



Wind and heavy rain ; cold ; no moths 



Rain all morning; cold, windy night; traps not lighted ! 



Cool; little wind; few moths flying early; too cold after 9 p.m. . . 68 



Clear, cool; bright moon; no moths flying 



Cloudy to 9.30; clear, cold; bright moon 



Moths flying in daylight after noon; few flying after dark 



No moths flying after dark; a few found feeding 



Few moths out after dark ; not attracted to lights 



Three Nociua c-nigrum caught; no others flying to light 



No moths flying to traps; traps taken up 



119 



171 



Total. 



82,488 



In all observations made at Willow Creek no moth was ever seen to 

 land on the ground on its way to a light trap as did the moths at Wilsall 

 the previous year. This may have been due to the fact that the tub 

 hid the light so it would not strike the ground, and in order to keep in 

 the path of light the moth had to fly straight to the trap. This was 

 usually the case, and for the most part moths flying to the traps came 

 on a straight line from 4 to 15 feet above the ground. They either struck 

 the arch or lantern or went straight on over the trap. 



On a still, dark, fairly warm night the moths would come to the traps 

 in varying waves of abimdance for which there was no apparent reason. 

 There would be a cloud of moths for a few minutes and then they would 

 come in scattering two's or three's. If the wind was strong no moths 

 were caught in the traps and no moths could be found moving about on 

 the ground. No moths were caught during a rain or ever after a rain, as 

 long as the ground and vegetation remained wet. When the moon 

 was bright, moths were not caught nor were any seen flying, though they 

 would start the minute the moon went behind a cloud. Practically no 

 moths were caught after the temperature had dropped below 58° F. 



