THE GIPSY MOTH ON CRANBERRY BOGS. 19 



The method to be used for the control of an upland infestation 

 must be decided by the owner of each bog. He must be governed by 

 the condition and particular surroundings of the bog in question. 

 Any of the foregoing methods should give satisfactory results if at- 

 tended to properly. 



SUMMARY. 



Infestations of gipsy moths upon cranberry bogs are due princi- 

 pally to wind dispersion of first-stage larvae, which occurs only when 

 conditions of wind velocity and temperature are favorable. The 

 time when maximum dispersion prevails is usually not longer than 

 from two to five days. Because of the activity of the young cater- 

 pillars in seeking food there are two daily periods of maximum dis- 

 persion, between 9 a. m. and 12 m. and between 2 and 5 p. m. 



Mortality of first-stage larvae is very great, large numbers perish- 

 ing from low temperatures, unfavorable food, predacious insects, 

 and disease. The embryos in all gipsy moth eggs deposited on cran- 

 berry bogs are killed by winter flowage, when the bogs are flowed 

 from December 1 to May 1. 



Upon deciduous foliage in general the feeding of the first-stage 

 larvae is upon the leaf hairs, but the injury to cranberry plants is 

 caused by feeding upon the terminal buds, and later upon the new 

 growth. As a rule vines recover more quickly from injury upon wet 

 bogs than upon dry ones. 



Flooding is the most effective method of control upon wet bogs; 

 but spraying is the only method which can be employed on dry bogs. 

 In order to obtain the most satisfactory results^ spraying should he 

 done before wind dispersion begins. 



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