1921.] PUBLIC DOCUMENT — No. 31. 33 a 



servations were made concerning the worm counts that precede 

 serious injury by this insect. 



The green span worm (Cyniatophora sulphurea) was also 

 unusually prevalent this season, and it completely destroyed 

 what promised to be a very good crop on several acres in Dux- 

 bury. Important new facts about the life history of this species 

 were learned. 



By extensive examinations and counts it was found that the 

 egg parasite (Trichogramma minuta) of the fruit worm was less 

 prevalent than usual. 



Important new observations concerning the habits of the 

 root grub (Aviphicoma vulpina) w^ere made. 



Five field meetings (in Rochester, Carver, Plymouth, Ware- 

 ham and Sandwich) were held with cranberry growers to dem- 

 onstrate the use of the insect-collecting net in discovering and 

 determining the severity of certain insect infestations in their 

 early stages. These meetings were planned as a special effort 

 in the control of the gypsy moth, but the other open-feeding 

 caterpillars often found damaging the bogs, such as span 

 worms and army worms, were also discussed. A supply of 

 insect nets had been prepared, and more than five dozen of 

 them were sold to the growers for use on their bogs. 



Weather Observations. — Weather observations were made as 

 in pre\ious years, in co-operation with the Weather Bureau, 

 daily reports being telegraphed to the district forecaster in 

 Boston. 



A new method of making minimum temperature calculations 

 for frost predicting, based on the Station records of 1913 to 

 1917, inclusive, was published in the '' Monthly Weather 

 Review" by the writer. Further records and studies were 

 made during the season for the purpose of testing and im- 

 proving this method. In forecasting for the local cranberry 

 growers the method proved accurate enough to be very useful. 

 Heretofore opinions concerning possible frosts have been given, 

 with a few^ exceptions, to the local growers and those in the 

 town of Carver only, the distribution of the warnings in Carver 

 having been made possible by the generous co-operation of Mr. 

 L. M. Rogers, manager of the Atwood Bog Company. This 

 season, through the courtesy of the New England Telephone 



