573 NEW JERSEY AGRICULTURAL COLLEGE 



sidered a safe period for that purpose, and water may be safely drawn 

 from such vines May 10th. 



Vines uncovered for a week have reached the normal, outdoor con- 

 ditions, and sound eggs will hatch in due course if development was 

 not started under water — that is, a bog from which the water was drawn 

 April 1st would develop eggs at the same time as on vines that had 

 remained uncovered. A bog drawn April 20th would begin to develop 

 eggs a week later than the normal date, say May 1st, and hatching 

 would not be universal until May 8th. 



Two weeks under deep water — eighteen inches or more — at a tem- 

 perature of 60°, will destroy the vast majority of all the eggs of 

 Eudemis, the result being due to some physical influence and not to 

 a favoring of larval development, as I had believed from previous 

 observations. 



To determine the period of drawing water from a bog infested by 

 black-heads, where reflowing is not possible, test the water temperature 

 at a two-foot depth, beginning about April 15th. When it reaches 

 60° allow it to remain for two weeks longer. 



PRACTICAL SUGGESTIONS. 



The observations made during the latter part of 1901 and the early 

 part of 1905 have led me to believe more firmly than ever in the 

 importance of keeping the immediate bog surroundings, and especially 

 all dams, as free as possible from cranberry vines. There should not 

 be on the bog itself any point that is not completely water-covered; 

 and this will prevent centers of infestation iov Teras, or yellow-head, 

 start. So far as possible the brush should be cleared up, even into 

 the woodland, and that will do away with hiding and breeding places 

 for species that resort to the cranberry as an alternate food plant. 

 In general, the cleaner the bog and its surroundings the easier it is 

 to control the pests. 



As to the management of the water, so many considerations enter 

 that it is somewhat unsafe to give positive advice. Every grower 

 must know Just how much water he has, how much he can do with it 

 and what points he means to gain. 



Speaking only from one point of view — that of insect control — when 

 there is water enough to reflow completely I would advise drawing no 

 later than April 1st. That will give the bogs a chance to start slowly 



