EXPERIMENTAL WORK WITH CRANBERRIES. 53 



The Diptera listed in this table are named according to Aldrich's cata- 

 logue. Prof. C. W. Johnson of the Boston Society of Natural History- 

 has adopted changes in their names as follows: CarceUa pyste instead of 

 Exorista pyste; Phorocera claripennis instead of Euphorocera claripennis; 

 and Exorista robusta instead of Tachina robusta. 



A small Trypetid was reared from cranberries in small numbers last 

 year. Mr. F. L. Thomas, a graduate student at the Massachusetts 

 Agricultural College who is making an exhaustive study of the Trypetidse 

 of New England, has determined this insect to be a small variety of the 

 apple maggot (Rhagoletis pomonella Walsh). 



Experimental Insect Work. 

 The experimental Avork with insects has been confined mostly to the 

 flowed-bog fireworm (black head cranberry worm) and the fruit worm. 

 The work with these two insects is here discussed in order. 



The Flowed-bog Fireworm {Rhopobota vacciniana (Pack.)). 



In last year's report on this insect, the successful results obtained in the 

 treatment of a certain large bog by holding the winter flowage late (until 

 June 2) and then reflowing about three weeks later to destroy an infesta- 

 tion were fully discussed . A somewhat similar procedure was carried out 

 on another but smaller bog this season with much less satisiactory results, 

 due probably to the fact that the reflowing was done too soon. The 

 results of this treatment, all things considered, seemed, however, to be 

 suflBciently successful to support the belief that where this method of 

 treatment can be applied it will be found at least a fairly satisfactory one. 

 The reflowage should evidently be continued for about forty-eight hours 

 in this treatment. 



The ideas advanced in last year's report, as to the way in which the 

 bunching up of the hatching of the eggs of this insect is brought about 

 bj- the late holding of the winter flowage, were evidently erroneous, as 

 shown by observations made this j'^ear. Tests with thermometers made 

 during the June reflows of the station bog showed that there are greater 

 differences of temperature among the vines of a cranberry bog when the 

 bog is flowed than when it is open to the air, the conditions in this respect 

 being exactly the reverse of what they were last year presumed to be. It 

 now seems probable that the bunching of the hatching bj^ the late holding 

 of the water is brought about mostly by a retardation or prohibition of 

 hatching for the first eggs that reach or approach the hatching stage. It 

 seems evident that the worms from any eggs, which might become far 

 enough advanced to hatch under water, would drovAOi soon after hatching, 

 and it is not impossible that this is what really happens to the eggs soonest 

 developed while the eggs of slower development are catching up with them 

 as the warming up of the water in the late spring allows them to develop. 

 It is, of course, evident that the whole hatching process is naturally more 

 rapid under the hot sun of June than it is when the development of the 



