1923 



ENTOMOLOGICAL SOCIETY. 



15 



the trap can readily be looked upon as those coming out of the material ploughed 

 down and surrounded by the trap. The observations were made early in the 

 morning and scant opportunity was given for moving from one side of the trap 

 to the other. The numbers recovered by the trap, together with those later 

 recovered from the enclosed refuse from below ground, reasonably approximated 

 the expectation upon an area of this size. Any lateral movement underground 

 would be of little consequence and would equalize itself. 



Table I summarizes the weekly recoveries from each entire trap of the 

 series for the period under observation. Table II summarizes the records of the 

 larvae recovered from the inside of the traps and from the material below 

 ground within the area enclosed. The percentages are based upon the assump- 

 tion that the larvae recovered from the inside of the trap were those coming 

 up from enclosed stalks and stubble. 



Table I — Summary of Larvae Recovered in Two-way Recovery Traps above a Series of Plough- 

 ings in 1922. 





Total Larvae Recovered in Traps by Weeks. 





Date of Ploughing 





JO 



OS 



ON 



ro • 



6s 



M3 



+JO 



o2 



CN O 



o2 



On 



CO >> 



O 



o 



o 

 o *"! 

 -- 1 > 



. o 



2S 



^ > 



. o 



£2 



Total 



Sept. 28 



39 



19 



23 



3 

 12 

 49 



3 



6 



39 



18 



l 



7 



9 



17 



4 



4 



3 



24 



16 



10 



2 







2 

 3 

 1 

 1 

 1 

 1 



2 

 2 

 2 

 4 

 3 

 2 

 4 



71 



Oct. 6 



55 



Oct. 12 



126 



Oct. 19 



56 



Oct. 26 



18 



Nov. 2 



5 



Nov. 9 



5 











zed 





336 





















Table II — Summary of Larvae Recovered inside Two-way Recovery Traps above a Series of 

 Ploughings in 1922. The recoveries are from the trap itself and from the ma- 

 terial below the ground, examined November 20th, 1922. 





Total Number 



of Larvae 



Recovered Inside Traps. 





Above Ground 



Below Ground 



Total Recovered 



No. 



Per cent. 



No. 



Per cent. 



No. 



35 



85.36 



6 





14.63 



41 



27 



61.36 



17 





38.63 



44 



52 



67.53 



25 





32.46 



77 



23 



29.87 



54 





70.12 



77 



11 



12.5 



77 





87.5 



88 



3 



10.0 



27 





90.0 



30 



4 



12.5 



28 





87.5 



32 



A study of the totals, recovered from inside the traps, indicates a progressive 

 increase of from 41 to 88 larvae from the ploughings up to October 26, there- 

 after a marked decrease in totals. This is due, in a large measure at least, to the 

 fluctuating larvae population and to the amount of refuse in different parts of 

 the field. It need not seriously interfere with the general value of the per- 

 centages. 



