Nov. 5, 1921 Pale Western Cutworm 303 



ground from 2 to 15 feet from the light and then crawled toward it, 

 where they could be easily picked up. As soon as it became totally dark 

 the moths came to the light so rapidly that two men could not keep them 

 picked up, and from 9 o'clock until midnight 282 females and 164 males 

 of P. orthogonia were placed in rearing cans or killing bottles. This by 

 no means represented the total number that came to the light, for hun- 

 dreds escaped. Many different species of noctuids were attracted to the 

 light, but fully 95 per cent were P. orthogonia. Ten of the females thus 

 captured averaged 132 eggs. (Table II.) 



In another part of the same field a Duro moth trap was run through- 

 out the nights of August 26 and 27, 19 19, and each morning the pan was 

 well filled with Porosagrotis orthogonia moths. During the two nights 

 4,900 moths were caught, of which 4,200 were males. It is difficult to 

 understand the preponderance of females caught at the larger light 

 between 9 and 12 p. m. and the very small percentage of females caught 

 at the smaller light during the entire night. 



Experiments with trap lights were conducted on a somewhat larger 

 scale at Willow Creek. A trap was designed which was made up of 

 utensils commonly found on every farm and which would serve other 

 purposes when not in use as a trap light (PI. 30, B). It consists of a 

 No. 2 galvanized-iron washtub and a No. 2 barn lantern. In addition, 

 a galvanized-iron arch is made which fits across the tub and serves the 

 dual purpose of deflecting the moths and holding the lantern. When 

 the arch is wired firmly and the lantern swung in place the flame of 

 the lantern is just above the edge of the tub. "W^Tien set in place, the 

 tub is staked down to prevent its being blown over, and about 4 inches 

 of water are poured into it. About }i to }{ inch of kerosene is floated 

 on the water to kill the moths which fall into it. 



Eleven such traps were put out at Willow Creek, and observations 

 were made during the flight period of Porosagrotis orthogonia. Two 

 traps for catching moths alive were also used, and when these showed 

 that P. orthogonia was beginning to fly the tub traps were put out on 

 fields that had been heavily infested with worms. 



During the first few nights the catches were small and the moths 

 were counted. The numbers increased nightly until the height of 

 flight, which was from August 19 to 24, inclusive. The night flight 

 gradually decreased after the latter date. When the numbers became 

 too large to count they were estimated, and during the height of flight 

 they were measured in pints. As a pint measure holds from 962 to 1,000 

 moths, the measuring of moths gave a fairly accurate count. During 

 the heavy flight several of the traps ran as high as 4,000 moths in a 

 single night. The entire season 's catch of Porosagrotis orthogonia moths 

 in the 11 traps was 82,488. The catch on individual nights is shown in 

 Table V. 



