14 BULLETIN 1093, U. S. DEPARTMENT OF AGRICULTURE. 
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 
larvae 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 larvae 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 o£ 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 gra\ T ity 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- 
