1922 ENTOMOLOGICAL SOCIETY. 15 



We consider light-traps to be unsatisfactory as a general method of control 

 on the prairies for the following reasons : — 



1. They require attention twice daily. 



2. They are somewhat expensive to operate. 



3. They are practically ineffective during periods of full moon. 



4. They are not well adapted to a windy country. 



5. For the species under consideration they catch too small a percentage of 

 females. 



Molasses Troughs. 



This method was suggeste'd by the experiments conducted by Dobrovljansky* 

 for the control of E. segetum in Eussia. Early in September 1920, three gal- 

 vanized iron troughs, 2 feet long and 6 inches wide and deep, were set out in a 

 badly infested area. Each was half filled with a 66% solution of molasses in water. 

 On the first night they captured a total of 382 moths o.f which 135 were females 

 of P. orthogonia. A slight crust had formed on the surface of the molasses by the 

 following night when 16 moths only were retained. Of these 8 were females. It was 

 obvious that we might be attracting to the field moths that we were unable to 

 capture and that possibly our troughs were doing more harm than good to the owner. 



Attempts to improve the consistency of the molasses solution failed to give 

 satisfactory results. In a 50% solution many moths swam to the sides and escaped 

 while any stronger solution crusted over in a very short time. Some twenty 

 troughs were used in 1921, and attempts were made to retain the moths in weak 

 solutions by the addition of vegetable and other oils, with tanglefoot arid with 

 poisons, but without success. 



This method was early abandoned for the following reasons : 



1. The troughs require very frequent attention. 



2. A great many of the moths escape. 



Poisoned Molasses. 



P. orthogonia comes very readily to "sugar" applied to fence posts. A fence 

 post can be kept permanently "sugared" every evening for from ten to fourteen 

 days by means of a simple apparatus. The only material required is a quart bottle 

 with a cork to fit, 6 inches of lamp wick and a small piece of absorbent cloth. The 

 bottle is filled with the sugaring mixture and the end of the wick, which has 

 first been well saturated in the mixture, is inserted. A well-fitting cork, that 

 has been slightly flattened on one side by cutting away a small portion with a 

 knife, is pressed fairly tightly into the bottle with the flattened si'de next to the 

 wick. The bottle is then inverted and wired or tied to the west side of a fence 

 post, and the free end of the wick is nailed to the post through a piece of absorbent 

 cloth. When a rapidly killing poison is used, and it is desired that material 

 obtained be preserved, a partial funnel of mosquito netting or paper can be attached 

 to the post. A modification, suggested by Mr. 'Carter, is to replace the cloth 

 with a shallow pan made from a tomato can. This forms a teservoir for any 

 surplus flow of poison. 



The bottle is fastened to the west side of the fence post in order that it will 

 not be exposed to the direct rays of the sun till the afternoon. The heat then 

 causes its contents to expand and to drive some of the liquid down the wick and 

 on to the cloth. This action usually continues till nearly sunset and it liberates 

 sufficient bait to attract moths throughout the night. After the sun has set a 

 reverse pressure in the bottle draws in sufficient air to replace the expelled liquid. 



*Extract in Rev. applied Ent. Series A. Vol. I, page 490, 1913. 



