4 BULLETIN" 554, U. S. DEPARTMENT OF AGRICULTURE. 



of the runners has occurred, in a number of bogs it has been noted 

 that such areas develop more rotten fruit than do adjacent vines in 

 healthy condition. The weakening of the vines apparently tends to 

 make the fruit more susceptible to fungous attack. 



In severe cases of girdler feeding the vines may become so loosened, 

 or so badly eaten and severed, that they may be rolled back with 

 slight exertion, exposing the bare trash beneath. 



Girdled vines are often found on which injured portions, where 

 the bark has been abraded, are covered with white cottony material ; 

 these are the waxy coverings of mealy bugs {Pseud ococcus adonidum 

 L.), and as they are rarely found on healthy vines they should be 

 classed as secondary pests. 



The specific injury caused by the feeding worms is due to their 

 eating through the bark of the runners into the wood, which often 

 occurs to such an extent that the runner is completely severed. (PI. 

 Ill, A, B.) Gnawing the bark completely around a runner will also 

 kill that part of the plant beyond, provided no other roots nourish 

 this part. Kunners are often seen which have been tunnelled for 

 short distances by this insect, and some are eaten down to mere 

 splinters. The fine roots as well are eaten, but to a less extent than 

 is the woody part. Feeding marks are sometimes found on the 

 crowns of the plants where they arise from the hills as originally 

 set. Practically all of the feeding, however, is done by the larvae 

 in a concealed position — in the trash which is found beneath the 

 vines, which consists largely of fallen leaves, pieces of vines, and 

 other debris, and forms a mat over the runners, affording the girdlers 

 excellent protection from parasitic insects. 



The feeding marks of the cranberry girdler should not be confused 

 with those of the cranberry rootworm (Rhabdoptems picipes Oliv.), 

 which feeds on the small roots and root hairs and on the runners only 

 to the extent of eating the bark, usually on the side which touches 

 the ground. In general, the rootworm feeds below the surface of 

 the ground, whereas the girdler feeds above the surface but hidden 

 in a layer of trash. The excrement of the girdler in badly injured 

 areas is very abundant, appearing in masses, which indicates that 

 the larva feeds for a considerable length of time without materially 

 changing its location. Often the excrement, intermixed with bits of 

 trash, will be found with silken threads woven loosely through it, 

 and these rude galleries probably constitute a protective covering for 

 the worm during the feeding period. Scudder (5) figured a cylin- 

 drical, upright case for this larva occurring on grasses, and Fer- 

 nald (8, p. 150) speaks of a vertical tube, constructed of bits of 

 vegetable material held together by silk, but neither of these larval 

 cases has been found on New Jersey cranberry bogs, and for this 

 reason the larvae are described as being naked. 



