ENTOMOLOGY 101 



margin. The hind wings are much broader and of a uniform 

 silvery gray. When the moth is at rest the wings are so closely 

 wrapped around the body that it looks like a narrow whitish cylin- 

 der about three-quarters of an inch in length. 



The young worm is very active and strong, and at once be- 

 gins the construction of the silken tube reenforced by bits of vege- 

 tation, in which it lives. It works about the running portion of 

 the plants extending along the surface of the sand in the stratum 

 of fallen leaves which always cover an old cranberry bog and from 

 which the delicate clusters of new rootlets take their rise. Every- 

 where over an infested area, but especially along its borders, these 

 worms can be found in filmy silken galleries following the pros- 

 trate stems of runners, into the surface of which they eat their 

 way, destroying the vital part of the plant and, especially next to 

 the base of the runners, deeply girdling the stem. They grow 

 rather slowly, and not until November do they make their course 

 cocoon of mingled sand and silk that serves as winter quarters. 



It seems probable that in Massachusetts there is only one 

 brood of the moths which is active in July. In New Jersey, on the 

 other hand, the moths have been found in every month from about 

 May 21 to the middle of September. There must be, therefore, at 

 least two broods, which develop very irregularly. With this dif- 

 ference in the life cycle in the two States there is an evident di- 

 vergence in food habits, for there is no such destruction of large 

 tracts in New Jersey 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 cran- 

 berry plantation, but also by the direct evidence of an investigator 

 who actually bred it on the common grasses and found further that 

 the worms would eat freely of sheep sorrel. The cranberry feed- 

 ing habit seems to be, therefore, a somewhat local characteristic 

 and this gives hope that by persistent work this bog variety may 

 be in large part 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 only a foot 

 or two across will remain for two or three years in succession with- 

 out becoming enlarged, but rather it will become closed up by run- 

 ners from the adjacent healthy vines. Larger areas tend to become 

 larger, new vines dying from the edges each year. 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. 



It is quite obvious that insecticides are not available here, be- 

 cause of the concealed feeding habit, and that resort must bo had 

 to more direct methods. The suggestion is therefore made that, 

 immediately after the fruit is off, infested bogs be flowed and bo 

 kept covered for at least a week, and bettor two weeks. This should 

 be effective against these worms and harmless to the vinos. While 



