ANNUAL REPORT, 1938 39 



Wareham, were seriously affected by this insect in the summer of 1938, the 

 infested areas comprising about 110 acres in all. The net -counts of the beetles 

 on these bogs ranged from 33 to 875 to 50 sweeps. All the infestations were on 

 the Howes variety, except one on Holliston and one on Early Black. The beetles 

 did not appear in full numbers until the middle of August, even on bogs from 

 which the winter water had been let off early in April. 



Derris applied in various ways both in sprays and as dusts failed to effect a 

 good kill of the beetles. Zinc arsenate, 2 pounds to 100 gallons of water, 250 

 gallons to the acre, failed to give a good kill, possibly because of heavy rains a 

 few hours after the treatment. 



As in 1936 and 1937, arsenate of lead was very effective. Evidently 3 pounds of 

 this poison (dry) to 100 gallons of water, 250 gallons to the acre, is about the 

 right spray for this insect. If it is applied in the middle of August (when 

 it will be most effective) and the berries are not picked before October, the lead 

 and arsenic trioxide residues on the fruit should not be above the present legal 

 tolerance (lead, .025 grains; arsenic trioxide, .01 grains per pound of fruit) unless 

 the rainfall in late August and September is definitely below normal. 



One grower sprayed some Howes vines for this insect on August 23, 1938, using 

 6 pounds of dry lead arsenate to 100 gallons of water and applying 250 gallons 

 to the acre. The rainfall was very abundant in September. Most of the sprayed 

 berries were picked on September 26 and two respresentative samples of this 

 fruit were analyzed for residues by the Fertilizer and Feed Control Division of 

 the station at Amherst. Some of the sprayed berries were left unpicked and the 

 bog was completely flooded from September 27 to October 2, inclusive. Two 

 representative samples of these berries, picked as soon as the vines were dry 

 from the flooding and on areas bordering directly and respectively on those from 

 which the previous samples were gathered, were also analyzed for residues. The 

 residues, both lead and arsenic trioxide, on all samples were well below the legal 

 tolerance. It was evident, however, that the water removed over half the lead 

 and two-thirds of the arsenic trioxide. These results confirm those of 1937^ 

 and show that to flood for several days is a good way to reduce the spray residues 

 on cranberries when arsenate of lead has been used without an adhesive. 



Residue in grains per pound of fruit 



Before flooding After flooding 



Lead Arsenic Lead Arsenic 



trioxide trioxide 



Sample 1 0105 .00462 .005 .00149 



Sample 2 015 .00561 .006 .00187 



Cranberry Weevil {Anthonomus musculus Say). The weevils were found on 

 some bogs in numbers giving insect-net counts of 500 to over 1000 per 50 sweeps. 

 They begin to hibernate soon after the middle of August and are hardly to be 

 found in the fall. 



The Atlantic Cutworm {Polia atlantica Grote). A considerable infestation of 

 this species appeared on a bog in West Wareham and a bog in South Easton in 

 1938. The winter flowage had been held on these bogs till the last week inMay. 

 Most of the worms reached full growth and began to go into the ground to pupate 

 by the first of August, but a few continued to feed on the cranberry foliage till 

 August 11. The description follows. 



Full-grown worm: Length, one and a quarter inches. General color, brown of 

 varying shade above and pale brown or pale greenish below. Head brown, much 



^Mass. Agr. Expt. Sta. Bui. 347, p. 43, 1938. 



