THE BLACKHEAD FIREWORM OF CRANBERRY, 37 



Vines which are rather heavily infested will require the first year 

 all three applications, as outlined above, and an additional fourth 

 application, which should be made during the first two weeks of 

 July. This last spray is designed to give protection, both to the 

 berries and to the upright tips in which the fruit buds for the fol- 

 lowing year's crop are forming, against late hatching larvse of the 

 first generation and the first larvse of the second generation. It is 

 also designed to kill many of the moths of the first generation, and 

 it should, therefore, be timed so as to come within the limits men- 

 tioned, as it is about this time that the moths are flying in largest 

 numbers. By careful spraying with an outfit like that shown in fig- 

 xire 13, one application at this time will clean a bog of fireworm moths 

 and thus prevent a large number of the eggs of the second generation 

 from being deposited. 



Kind of EQxnPMENT. 



A 50-gallon wheel-barrel outfit, with a strong pump, will usually 

 be found sufficiently large for bogs up to several acres in extent. For 

 larger bogs the power outfits of various sizes will be most economical, 

 and in order to avoid dangerous delays at spraying time one should 

 he sure that the parts are not only durable but easily accessible and 

 replaceable as well. 



Any arrangement of nozzles and manner of spraying the bog that 

 will insure thorough application of the spray as previously outlined 

 and at the same time cause a minimum injury to the vines from walk- 

 ing or dragging the hose over them will be satisfactory. 



After a consideration of the factors which influence the hatching 

 and development of the blackhead fireworm (see pages 8-9), it would 

 seem reasonable to suppose that a covering of water held over the 

 vines until late in the spring, say until about April 10 to 15, together 

 with the thinning out of thickly vined bogs, would have a very bene- 

 ficial effect. It would also facilitate good control work by grouping 

 the hatching of the larvse. In view of the fact that it is also con- 

 sidered a good horticultural practice on the Pacific coast, this method 

 of bog management in connection with spraying is to be recommended 

 wherever it is practicable, especially on bogs which are badly in- 

 fested with fireworms. 



SUMMARY AND CONCLUSIONS. 



The blackhead fireworm {Rhoyohota naevana Hiibner) is the most 

 important pest of the cranberry on Pacific coast bogs. It is found 

 also on native cranberry vines well isolated from cultivated bogs, 

 but was doubtless introduced on these cultivated bogs on cuttings 

 from eastern cranberry districts. So far as known on the Pacific 

 coast, it feeds only on the cranberry. 



