218 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



Among substances employed with the hope of obtaining an immediate 

 killer were various arsenicals, soluble strychnine, copper sulphate, forma- 

 lin, 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 det- 

 errent effect in the field when they were employed in weak solutions. 

 Various objections to most of the forms of arsenic that are readily a- 

 vailable to a farming community decided us to adopt commercial fly 

 pads, at the rate of one pad per quart of solution, as the most satisfac- 

 tory source of supply. At this strength the arsenic is very slightly deter- 

 rent and there is no precipitation. The pads can either be soaked in 

 the solution over-night or be 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 was unfavoiu-able for bait traps. A very dry summer had 

 resulted in the failure of many crops and had seriously hampered siimmer- 

 fallowing, with the result that nearly all classes of fields were covered 

 with Russian thistle. This was flowering at the time of flight. Noc- 

 tuidae feed freely on these flowers, but the favourite food plant in Al- 

 berta 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 

 attractive to overcome the predilection of the moths for these flowers. 

 With the addition of eight drops of amyl acetate per quart of the solu- 

 tion, both sexes of P. orthogonia could be attracted to feed on the bait 

 despite the close proximity of a strong counter attractant. 



The abundance of feeding is very variable and we did not obtain 

 very definite data upon the probable catches made by our experimental 

 traps. At night there were frequently as many as 20 to 30 moths, of 

 which over 50% were female, feeding on a single trap at a time when 

 very few were attracted to troughs of molasses. By day males were 

 found feeding at all hours, though they were most abundant between, 

 the hours of 2 and 5 P. M. Females appeared less frequently in. 

 the morning and were seldom seen in numbers till about 4 P. M.^ 

 by which time they visited the traps freely and were nearly as numerous- 

 as the males on golden-rod blossom. 



We did not discover that quassia would retain the majority of moths 

 that visited a trap till too late in the season for this to supply us with, 

 many data. 



