96 INSECTS AFFECTING VEGETATION 



will stand a quarter or even a half an inch start under water with- 

 out danger unless the water is drawn on a very warm day, and then 

 there is danger of scalding. The further advanced the plants the 

 greater that danger becomes; hence great care and good judgment 

 must be exercised when this measure is adopted. Fruit-bearing up- 

 rights can not be safely permitted to make more than a mere start. On 

 a sloping bog, where the water is deep at the gates and becomes shal- 

 low at the edges, the water may be gradually drawn from the bottom 

 so as to leave the warmer surface water, and in this way practically 

 all the eggs will come under the influence of the moist heat that 

 favors their development. 



Carefully carried out, this measure is often very effective; the 

 warmth favors the development of the embryo within the egg, and 

 when the worm hatches it drowns. Occasionally a specimen may 

 bore into a leaf and so maintain itself twenty-four hours or more, 

 but usually it stifles without getting even a bite. Sometimes badly 

 infested bogs are completely freed by this method without apparent 

 injury to the setting of fruit, yet at times the crop is reduced one-half 

 by holding a little too late. In the latter case, however, the crop 

 had been destroyed by the insect for several years in succession, 

 and the owner was quite willing to sacrifice 50 per cent if thereby 

 he got rid of the insect, as he did. This method should be em- 

 ployed only when reflowing is not possible. 



When the supply of water is abundant above the bog area, so 

 that a pond or reservoir may be formed, both the yellow and black- 

 heads may be completely controlled by drawing the water early, 

 waiting until all the eggs have hatched and some of the worms are 

 nearly half grown, and then re-covering the bog with water for 

 forty-eight hours. This method is so simple and so absolutely ef- 

 fective that the larger growers are adopting it almost universally, 

 and few new bogs are laid out anywhere without considering the 

 matter of reflowage and providing for as good a control of the 

 water as possible. Under proper control the water may be drawn 

 from the bogs when the best interests of the plant demand it with- 

 out any regard to insect conditions. If worms appear in any num- 

 ber toward the end of May, the bogs are reflowed, and rarely is 

 this necessary more than once in three years. Only when the bog 

 area is small and the surroundings are very bad is annual reflow- 

 age needful. For a complete effect the vines should remain cov- 

 ered forty-eight hours, because it requires some time for the water 

 to penetrate the spun-up leaves so as to kill the worms. Many, 

 indeed, especially the half-grown blackheads, wriggle out, seeking 

 to escape when the water reaches them, but those nearing maturity 

 are less active, remaining at home until the water surrounds them 

 and they simply can not get out. Covering the bogs should begin 

 in the late afternoon and should be completed before next morn- 

 ing, if possible. On a rainy day it may begin at any time, the 

 object being merely to prevent the sun from boiling the young 

 ehoots. So drawing off the water should also begin in the early 

 afternoon, and the bog should be practically dry the morning after. 



