EXPERIMENTAL WORK WITH CRANBERRIES. 



57 



Study of Control for Flowed Bogs. 

 No verj' definite advance in our ideas concerning the control of this pest 

 by flooding was made during the year. The recommendations given in 

 last year's report still stand with no substantial alteration. It was sus- 

 pected that the depth of the flowage had some bearing on its effect in 

 killing the worms within their cocoons, as it seemed reasonable to suppose 

 that the greater water pressure of a deep flowage would be more effective 

 in collapsing or penetrating the cocoons than would be the slight pressure 

 of a shallow flowage. To test this, different lots of fruit worms, spun up 

 naturally in their cocoons, were submerged to various depths in water 

 contained in long glass tubes 2 inches in diameter. The following table, 

 showing the results of some of these tests, is self-explanatory: — 



It will be seen from this table that nine days of submergence, after the 

 8th of October, appeared to have but little efifect on the worms at any 

 depth tested. The remaining tests, not recorded in this table, gave results 

 entirely similar. Possibly submergence earlier in the season would have 

 been more effective in killing the worms. Bogs bearing late varieties 

 could probably not, however, as a rule, be reflowed, after picking, before 

 September 25, and it hardly seems probable that a difference of two weeks 

 in the season would be sufficient to cause any marked difference in the 

 effects of submergence on this insect. It may, of course, be possible to 

 work in a flooding between the picking of the early and of the late varie- 

 ties, but general experience appears to cast doubt upon the advisability 

 of such a program. 



An interesting fact learned while making these submergence tests was 

 that the cocoons of the fruit worm are not at all impervious to water. 

 When carefully opened, after only a few minutes' submergence, they were 

 found to be wet inside, the water having apparently penetrated them 

 almost immediately. It now seems evident that the cocoon protects the 



1 And 1 doubtful. 



