224 MASS. EXPERIMENT STATION BULLETIN 180. 



to 1^ teaspoonfuls' to 40 gallons. The writer suggested only the arsenate 

 of lead, fearing arsenic would do harm. The latter was added by the fore- 

 man of the bog to do a thorough job, and fortunately no injury resulted. 



The wTiter visited the bog on July 20 and found dead rootworm beetles 

 in large numbers under the vines, most of them being in a dry and brittle 

 condition. Only a very few were crawling about. The cranberry foHage 

 on the infested area showed that the beetles had fed freely upon it. As 6 of 

 15 beetles, collected July 11 and kept at the station screenhouse, were still 

 active on the 26th, the condition of those found on the bog on the 20th 

 seemed to indicate that the spraying had been effective. This bog was 

 kept under observation until the end of the season, and no evidence of the 

 continued presence of the pest was discovered, it having been practically 

 exterminated by the treatment. 



Prof. H. B. Scammell has published a valuable bulletin on this insect.^ 



The Gypsy Moth {Porthetria dispar L.). 



Several quarts of egg masses were collected from trees late in December, 

 1915, and early in January, 1916, and divided into lots of about a half quart 

 each, two of these being put in cans ^\ith moist sand in the bottom and 

 placed in the basement of the station screenhouse for checks, the others 

 being enclosed in cloth netting sacks and submerged for the winter in 3 

 feet of water in a pond. 



The eggs of the check lots hatched almost perfectly. The dates on which 

 the various submerged lots were taken from the water, and the ^Titer's 

 estimates of the percentages of eggs that hatched, were as follows: lot 1, 

 April 2, 25 per cent.; lot 2, April 18, 20 per cent.; lot 3, April 23, 18 per 

 cent.; lot 4, May 1, 25 per cent.; lot 5, May 5, 20 per cent.; lot 6, May 

 13, 20 per cent.; lot 7, May 24, 5 per cent. The submergence did not 

 seem to kill the eggs as readily in these tests as in those reported last j'-ear. 

 This may have been due to the unseasonable coldness of the spring this 

 season, which probably caused the water in the pond to warm up more 

 slowly than usual. 



On May 29, 59 gypsy-moth caterpillars from one-eighth to five-six- 

 teenths of an inch long were submerged on the leaves of an oak branch 

 just as they were taken from the woods, in 8 inches of water in a washtub. 

 All but 3 of the worms clung to the branch and went down into the 

 water with it. At the end of a forty-three-hour submergence, 8 floated 

 on the surface, 4 had sunk to the bottom of the tub, and 47 still clung 

 to the leaves. These worms were watched for two days after the close 

 of the test, but only 1 of the 59 showed any sign of life. 



On May 31, 50 caterpillars from one-quarter to five-sixteenths of an 

 inch long were submerged, as before, on the leaves of an oak branch in 9 

 inches of water. All these worms clung to the leaves tenaciously when 

 submerged. After twenty-two hours in the water, 2 floated on the surface, 



> The Cranberry Rootworm, Bui. No. 263, U. S. Dept. Agr., 1915. 



