108 INSECTS AFFECTING VEGETATION 



extreme rapidity. As they can be used against the wind or while 

 the plants are somewhat damp there is practically no danger that 

 the fire will get away, and when the ground is frozen, the covering 

 of leaves and stalks is burned so rapidly that no heat gets to the 

 roots. Growers consider it desirable to keep a cover of vegetation 

 on the dams to strengthen or prevent them from washing, and this 

 method will destroy the egg-bearing vegetation without also de- 

 stroying the plants themselves. 



The Ideal Cranberry Bog. So much has been said of bog 

 conditions, and bog conditions so greatly influence the abundance 

 of injurious species of insects, that it may not be out of place to 

 describe briefly what a bog should be to make insect control easy 

 and certain. 



(1) The bog should be as nearly level as it can be made, so 

 as to require the least possible amount of water to flow it. A bog 

 that can be completely covered, by a 12-inch head is better than 

 one that requires 24, and when the difference in level of an area 

 is 5 or 6 feet or more it is better to make two bogs out of it, that 

 the lower may be reflowed from the upper and less than half the 

 amount of water be required. 



(2) Make no one bog 90 large that more than thirty-six hours 

 are required to cover completely, and no more than twenty-four 

 hours are required to draw the ditch level. 



(3) Build a reservoir or reserve a flooded area above the level 

 of the highest bog of a series sufficient to hold water enough to flow 

 at least the highest bog completely. The importance of this re- 

 quirement is so fully appreciated that miles of ditches have been 

 dug in New Jersey to tap streams at a higher level, and many acres 

 of swamp area have been created by raising contour lines to deepen 

 natural basins. In Massachusetts powerful pumps have been in- 

 stalled to pour water directly upon the bog or into a reservoir 

 above it. 



(4) Adjust bog levels so that the upper one of the series can 

 be completely emptied into the one below, and yet have the gates 

 and outlets so adjusted that any one bog may be completely 

 emptied without interfering with either those above or those below. 

 It happens not infrequently that one bog needs cleaning or other 

 attention while others do not. 



(5) There should be a broad, deep, marginal ditch between 

 the dam and the bog or between the bog and upland, and this ditch 

 should be always clean and at least partly full of w r ater. Many 

 kinds of insects can be altogether kept from the bogs in this way, 

 while grasshoppers and other insects are delayed until they can 

 fly. Then they are feeding on other things, and they do not often 

 change the food habits of their early life. 



(6) The dams and the edges of the uplands should be kept 

 as free as possible from vegetation that harbors cranberry-feeding 

 species. Cranberry vines should not be tolerated for an instant. 

 Huckleberry bushes are almost as bad, and these should be cleared 

 back for some distance where bog and upland join without an inter- 



