18 



BULLETIX 1093, V. S. DEPAETMEjSTT OT AGEICULTUEE. 



When light infestations are present and the immediate upland 

 border is clear of overhanging brush, border ditches may offer all 

 necessary protection, provided they are in proper condition. To be 

 effectual they should not be less than 15 inches wide and from 15 

 to 20 inches deep with the bog side of the ditch perpendicular and as 

 smooth as possible, in order to give little foothold to the crawling 

 larvae. If not detrimental to the vines or crop, a few inches of 

 water should be maintained in the ditch with a little crude oil on 

 the surface. The larvse dropping from the land side into the ditch 

 will become smeared with oil and suffocate. Should some larvae 

 reach the bog side and attemj^t to crawl uj) the smooth surface, being 

 weakened by partial suffocation they will drop back into the oil bath. 



c^.-r^^:: Earth 



Fig. 4. — Cross section of an upland trench, with, board in position. 



Should the infestation prove too heavy to be controlled by the oil 

 and water a board about 1 foot wide may be set against the smooth 

 surface of the bog side of the ditch, restine: on stakes driven in the 

 bog at an angle of 45 degrees, care being taken to make tight joints. 

 The underside of the board and stakes should be smeared with a good 

 coat of commercial sticky tree-banding material. It is obvious that 

 with an infestation heavy enough to require the use of the board, the 

 ditch might have to be frequently cleared of the dead bodies of the 

 larvae in order to remain effective. 



