CRANBERRY INSECT PROBLEMS. 29 



VINE-ATTACKING INSECTS. 



CRANBERRY GIRDLER.' 



The cranberry girdler is the most destructive of insects tliat attack 

 the vines and is the cause of hirge losses each year, particuhirly in 

 NcAv Jersey. Although the pest is rather common in Wisconsin, the 

 damage on cranberry bogs in that State has not been severe, probably 

 because the marshes are, as a rule, wetter than those in the Eastern 

 States. The girdler is distributed widely throughout the United 

 States and other countries and is known to many as a pest of grasses. 



Fig. 25.— Cranbprry girdler : Cocoons. Enlarged. 



Its known food plants are few, however, and it seems to have become 

 more destructive to cranberry than to any other crop. The work of 

 this insect on the bogs is very noticeable, but owing to the concealed 

 feeding habit of the worms few growers ever find them and not 

 infrequently the damage is attributed to other causes and steps to 

 control the worms are not taken. 



Character of Injury. 



Injury to the vines is caused by the feeding of the worms on the 

 stems and runners and, to some extent, on the roots. Not only is the 

 bark eaten but the wood itself is gnawed, frequently resulting in the 

 complete severing cf a runner. The plant at its crown is very liable 

 to be girdled, resulting in quick death of the leaves and branches 

 beyond. The feeding marks are usually associated with quantities of 

 castings, or excrement, more or less held together by strands of silk. 



The character of the injury is such that large areas of the vines 

 may be killed in the course of a single season, and if the worms are 

 left unchecked these areas will grow larger from year to year. 

 (Fig. 24.) Entire bogs are rarely, if ever, attacked. There appear 

 to be certain parts of every bog, particularly the higher and well- 

 drained parts, where the vines are underlain with large quantities of 

 trash, w4ich are more favorable for girdler development and it is 



■i Cramhufs hortueUus Hiibner. 



