38 MASS. EXPERIMENT STATION BULLETIN 168. 



The Black-head Fire-worm^ {Rhopobctx vacciniana (Pack.)). 



Arsenical sprays, well sweetened with saccharin, were tried against 

 this insect, but no advantage of any consequence resulting from the 

 sweetening was detected. 



The writer dislikes the idea of spraying for this pest. At best, it is an 

 expensive and injurious method of treatment. The general conditions 

 of the cranberry industry are making the use of less costly means of 

 control than spraying increasingly imperative for this insect as well as 

 for the "other common pests and diseases. The possibilities in this con- 

 nection are made more apparent in the discussion of bog management 

 included in this report. 



In last year's report (page 107), the writer suggested the possibility of 

 treating this insect satisfactorily by holding the winter flowage late 

 enough to kill its eggs, as often as an infestation developed sufficiently 

 to do serious damage, sacrificing the crop in the years of such late holding. 

 He has had the opportunity to observe the results of such late holding to 

 some extent this season. A New Jersey bog appeared to be satisfactorily 

 cleared of the pest by holding the water until the middle of June, and a 

 heavy infestation on a bog in Wareham was very greatly reduced by the 

 holding of a partial flowage until the 1st of July. In the latter case the 

 results, under the conditions, were so satisfactory that it seemed certain 

 that the bog would have been cleared entirely had all the vines been com- 

 pletely submerged. In neither case did the vines appear to be much 

 injured by the water. Those on the Wareham bog bloomed considerably 

 and came to the end of the season well budded and otherwise in good 

 condition, even producing a little fruit. 



The Cranberry Fruit Worm (Mineola vaccinii (Riley)). 

 Two netting sacks, each containing 160 cocoons (with worms) of this 

 insect, were submerged in a pond in 3 feet of water on January 15. One 

 of these sacks was taken from the water on March 31, and the cocoons 

 were opened on the same day and their contents examined, 40 per cent, 

 of the worms being found alive, almost a quarter of them being quite 

 active. The other sack was taken from the water on May 20, and the 

 contents of its cocoons were examined on the same day, not a single 

 live worm being found, most of them being more or less decomposed. 

 The results of these experiments are entirely in line with the common 

 experience of cranberry growers, which has for years indicated that the 

 fruit worm could not endure a prolongation of winter submergence far 



1 The American Association of Economic Entomologists, at its last annual meeting (Decem- 

 bsr, 1915), voted to adopt the terms "black-head fire-worm" and "yellow-head fire-worm" as 

 common names for this insect and Peronea minuta (Rob.), respectively, in place of the names 

 "black-head cranberry worm" and "yellow-head cranberry worm" formerly officially recog- 

 nized by it. As the writer finds the newly adopted names satisfactory, he abandons, in this 

 report, the terms "flowed-bog fire-worm" and "dry-bog fire-worm," previously used by him for 

 these insects. 



