14 BULLETIlSr 1093, U. S. DEPARTMENT OE AGRICIILTUEE. 



bog when the vines are disturbed. One may obtain an approximate 

 idea of the degree of infestation on his bog by either of the follow- 

 ing methods, the accuracy of the estimate depending upon the care 

 taken in performing the operation. 



Pan Method. 



Place a bright tin pan carefully among the vines, holding it with 

 the right hand, inclined to the right at an angle of 45 degrees. With 

 the left hand give the vines directly in front of the pan two or three 

 quick slaps ; then remove the pan and note the number of gipsy moth 

 larvse taken. Eepeat this operation every 10 or 20 feet, until the 

 whole bog is covered. By keeping a record of the number of larvae 

 taken and the number of times the pan was used, one may estimate the 

 degree of infestation quite accurately. 



Insect Net Method. 



The degree of infestation on bogs may be determined also by the 

 use of an insect net. Care should be taken to make even sweeps with 

 the net, covering the same amount of vine surface with each sweep. 

 By counting the number of larvse taken after making a number of 

 sweeps and estimating the area of vine surface covered by each sweep, 

 one may estimate the infestation on the bog as a whole. The accu- 

 racy of this estimate will depend on the care taken in making the 

 sweeps and the percentage of bog area covered. Whichever method 

 is used, the line of collection should be from the shore line of the bog 

 toward the center, as the infestation is usually heaviest nearer the 

 shore. 



CONTROL ON WET BOGS. 



It has been demonstrated that no hatching occurs from gipsy moth 

 egg masses placed among cranberry vines on bogs that are flowed from 

 December 1 to May 1, while check experiments have shown normal 

 hatching. It has also been found that egg masses placed under sand 

 on dry bogs fall only 6 per cent below normal hatch. 



These determinations were made during the winter of 1915 to 

 1916 and in 1917 by F. H. Mosher, who carried on experiments at 

 North Saugus. Mass., and East Carver, Mass., to obtain information 

 on this phase of gipsy moth investigations. 



It is, therefore, evident that the methods of control adopted by the 

 cranberry grower must be governed by the kind of bog infested, 

 whether wet or dry. Owners of cranberry bogs located near an 

 abundant supply of water, where flooding either by gravity or pumps 

 can be quickly accomplished, have at hand the cheapest and most 

 effective method for the control of this pest : First, by winter flowing, 

 by means of which the partially developed larvae in all eggs depos- 



