54 MASS. EXPERIMENT STATION BULLETIN 150. 



eggs and their hatching takes place in the cooler weather of the first half 

 of May, as usually occurs when the winter flowage is drawn off early. 



The general position taken in last year's report in regard to the practice 

 of spraying for this insect should probably be maintained. It seems pos- 

 sible, however, that instead of using Bordeaux mixture and Paris green 

 for this spraying it will be found best to use arsenate of lead alone, for 

 while some of the results with Bordeaux mixture have been satisfactory, 

 there seem to be indications, as hinted in the discussion of the fungous 

 work, that it may be, under some conditions at least, an injurious spray 

 to use. Experiments are planned to find out more exactl}^ about tliis. 

 On some bogs where Bordeaux mixture and Paris green were used on one 

 part and arsenate of lead on another, this year, the arsenate seemed to 

 give rather distinctly better results. 



We have not j'ct learned what is the best method of applying a spray to 

 a cranberry bog. There is considerable diversity of opinion and experi- 

 ments are planned along this line. It seems probable that in thick vines 

 a spray driven with a good deal of force wiU place poison where it will 

 have a more satisfactory effect in destroying this insect than will the 

 poison of a spray lightly applied. 



From observations made on a considerable number of bogs this year 

 the fire worm seems to be distinctly more injurious on vines of the Late 

 Howe variety than on those of the Early Black, and it seems probable 

 that the late Howe is a favorite variety with the pest. If this is the case 

 it is only an added indication that where bogs are being newly built it is 

 the part of wisdom to plant only one variety on a bog. It is now becom- 

 ing generally recognized that the planting of several varieties together 

 on the same bog causes more or less serious inconvenience in many ways. 



A detailed account was given in last year's report concerning the para- 

 sites and other natural enemies of this insect and concerning the bearing 

 which bog flooding has upon their effective acti\aty. In connection with 

 this, attention should have been drawn to the fact that when a bog is 

 reflowed after picking, the most conspicuous forms of animal life that are 

 driven ashore by the water, from the standpoint of their numbers, are the 

 spiders. The number of these forms seen by one looking for them on the 

 occasion of such after-harvest reflowing is reall}^ surprising, and it is 

 interesting to note that most of them, even on a bog of considerable size, 

 succeed in reaching the upland alive, as they are fitted to float lightlj^ 

 upon the surface of the water for considerable distances if need be. In 

 aU his examinations of bogs made during the process of the after-harv^est 

 reflow the writer has as yet failed to see a sufficient number of parasitic 

 insects driven up by the water to lead him to beUeve that they can have 

 nearly as important a bearing on the prevalence of the fireworm as do the 

 spiders. It is probable, however, that the presence of the parasites on a 

 bog is, in a sense, more affected by the flowing than is that of the spiders, 

 because they are probably far more liable to destruction by drowning 



