23 



there is no such destruction of large tracts in New Jersej^ as is found 

 in Massachusetts. That the insect is not specifically a cranberry feeder 

 is proved not only by the fact that it occurs not uncommonly many 

 miles away from any cranberry plantation, but also by the direct evi- 

 dence of an investigator who actually bred it on the common grasses 

 and found further that the worms would eat freely of sheep sorrel. 

 The cranberrj^ feeding habit seems to be, therefore, a somewhat local 

 characteristic and this gives hope that by persistent work this bog 

 variety may be in large jjart stamped out. 



An infested bog is rarely affected over its entire extent. Small 

 areas varying from a few feet in diameter to half an acre or more are 

 found here and there, and sometimes a little patch onl}^ a foot or two 

 across will remain for two or three years in succession without becom- 

 ing enlarged, but rather it will become closed up by runners from the 

 adjacent healthy vines. Larger areas tend to become larger, new vines 

 d3'ing from the edges each 3''ear. A restart over areas so killed out is 

 very slow, yet it does usually occur after the second year; but the 

 growth is apt to be irregular and requires some time before it comes 

 again into bearing condition. 



Remedial measures. — It is quite obvious that insecticides are not 

 available here, because of the concealed feeding habit, and that resort 

 must be had to more direct methods. Light traps to capture the 

 adults have proved unsatisfactory, very few specimens having been 

 taken in this way. Experiments show that the worm in its silken case 

 will bear submergence in water for over four days without fatal 

 results, and it is known that in its cocoon it bears submergence during 

 the entire winter. But the insect does not make this cocoon until 

 November, and a submergence of five days immediately after the 

 picking is completed destroj^s a great many. The suggestion is 

 therefore made that, immediately after the fruit is off, infested bogs 

 be flowed and be kept covered for at least a week, and better two 

 weeks. This should be effective against these worms and harmless to 

 the vines. While the ripening fruit is on, any water covering kept 

 on over twent3'-four hours would be apt to do material injury. 



An additional suggestion is that the actually infested area be com- 

 pletely burned off as soon as its extent can be determined. The vines 

 already attacked are doomed at best, and if in destroying them the 

 insect can be also killed the loss will be balanced by a greater benefit. 

 For this burning a gasoline torch may be employed, and the heat thus 

 applied directly to the point where it will be most effective. The use 

 of the torch will also prevent setting a fire that might injure other 

 portions of the bog, since it can be used when the vines are so wet 

 that they will not burn under ordinary conditions. The burned-over 

 area can be immediately reset and the actual amount of injury limited 



to a minimum. 



m 



