16 THE KEPOET OF THE No. 36 



Provided the variations in temperature are not too extreme, or .fermentation 

 too rapid, a quart bottle will run every evening for from ten to fourteen days. 

 We have tried several modifications of reservoir and methods of controlling the 

 flow of bait, such as the "drinking fountain," siphon, and gravity feed, but find 

 the inverted bottle to be as satisfactory as any. 



Having obtained a satisfactory apparatus, our next concern was to find a 

 suitable poisoned bait. As a basis a 10% solution of cane molasses was used in 

 all cases. This ferments within a few days of mixing. In the fall of 1920, ex- 

 periments were made in which the tlecantation from a saturated solution of white 

 arsenic was used as the diluent. This killed moths in the laboratory in from 8- 

 to 40 hours, but was found to he somewhat deterrent to feeding. 



When this solution was used in bottle traps moths fed on it and obtained suf- 

 ficient poison to cause their death within 24 hours. This was proved by captured 

 specimens. In the field, however, they all flew from the traps before 'dying. It 

 was hoped that some immediate killer could be obtained in order that we might 

 estimate the value of the traps, and be certain that gravid females were unable to 

 deposit their eggs before dying. It was also highly desirable that those who might 

 be using the traps as a practical means of control should be able to see some results 

 from their efforts in the form of dead moths. 



To this end we planne'd a series of experiments in 1921, but it was not until 

 nearly the end of the season that Mr. Seamans found quassia to be the nearest 

 approach to what we desired. Subsequent observations showed that this material 

 must be used in conjunction with some other poison. 



iVmong substances employed with the hope of obtaining an immediate killer 

 were various arsenicals, soluble strychnine, copper sulphate, formalin, mercuric 

 chloride, sodium cyanide in solution, and sodium fluoride. All of these failed to 

 kill in less than about 12 hours except in strengths that proved to be deterrent. 

 Arsenical poisons showed the least deterrent effect in the field when they were 

 employed in weak solutions. Various objections to most of the forms of arsenic 

 that are readily available to a farming community decided ns to adopt commercial 

 fly. pads, at the rate of one pad per quart of solution, as the most satisfactory 

 source of supply. At this strength the arsenic is very slightly deterrent and there 

 is no precipitation. The pads can either be soaked in the solution over-night or 

 cut into strips which are inserted into the bottles. Moths captured while feeding 

 on bottles so poisoned 'died in from six to one hundred hours, depending upon the 

 amount of feeding prior to capture. The majority of poisoned moths died within 

 36 hours. Checks taken from unpoisoned bottles lived for an average of 130 

 hours without subsequent feeding. 



The season Avas unfavourable for bait traps. A very dry summer had resulted 

 in the failure of many crops and had seriously hampered summer-fallowing, with the 

 result that nearly all classes of fields were covered with Russian thistle. This was 

 flowering at the time of flight. Noetuidre feed freely on these flowers, but the 

 favourite food plant in Alberta appears to be golden-rod, which flourishes in 

 restricted areas of waste land. Experiments with traps placed in these golden-rod 

 areas showed that fermenting molasses, when used alone, was not sufficiently at- 

 tractive to overcome the predilection of the moths for these flowers. With the ad- 

 dition of eight drops of amyl acetate per quart of the solution, both sexes of 

 P. orthogonia could )be attracted to feed on the bait despite the close proximity of 

 a strong; counter-attractant. 



