192 INTERNATIONAL CONGRESS OF VITICULTURE 



Emphasis has been placed on the period of emergence for the time of 

 spraying is dependent upon it. This phenomenon together with the time the 

 eggs are deposited constitute an important portion of the seasonal history of 

 the grape root-worm so far as remedial measures are involved. For this 

 reason it is very necessary that these dates be accurately determined by 

 grape growers themselves for they differ with the locality, soil, latitude and 

 humidity. For several years the writer has made an effort to correlate the 

 time of emergence with well marked conditions of the vine, but so far no 

 condition, that is constant has been observed. The size of the berries and 

 the time the fruit has set to the time of emergence of the beetles is found 

 to be variable, depending on moisture and temperature. Nothing so well 

 defined as the relation between the time of spraying for the codling moth 

 and the falling of the petals of the apple has been found for grape spraying. 

 During normal years sprayings made about one week after the fruit has set 

 have been found to be very effective but this will not be true for abnormal 

 years. Fortunately the feeding of the beetles is so conspicuous that grape 

 growers should have little trouble in noting the time of emergence sufficiently 

 accurately for practical purposes. Growers should have sprayers and ma- 

 terials ready for immediate use by the time the fruit has set, then by careful 

 observation the exact time for spraying can be determined and the material 

 applied when it will be most effective. 



Feeding habits. The adults usually do not begin feeding until about a 

 day after emergence. During the first two weeks of their life as adult they 

 feed ravenously but later feed much less, especially after dispersion has 

 taken place. The adults feed only during portions of the day, remaining in 

 hiding near the axils of the shoots much of the time. A favorite position is 

 in the axils near the upper wire in the Chautauqua system of training. 



Egg deposition. Shortly after mating the females begin to deposit eggs, 

 these eggs are placed chiefly under the loose bark of the canes but are 

 found on all the woody portions of the vine above ground. The eggs are 

 tucked away between the living bark and the loose or corky layers which 

 cover the vine. Seldom do we find eggs laid in exposed situations either on 

 the foliage or on the wood. The number deposited in a cluster varies greatly. 

 In 1914 the numbers of eggs in 164 clusters were counted and the range was 

 found to be from 1 to 66 with a mean of 24. 



The eggs hatch in about two weeks after being deposited although this 

 time varies greatly because of differences in temperature. 



Larva. The small larva after hatching crawls about on the bark and 

 soon drops to the ground where it immediately burrows into the soil. It 

 works its way to the roots of the vine on which it feeds. It grows rapidly 

 and often reaches full size by November. If it does not attain its full growth 

 by that time it usually does so the following spring. In several instances 

 Johnson and Hammar found that the larvae lived until the second summer 

 before changing to pupae. 



The latter part of October, the larvae burrow into the soil to the depth 

 of about a foot or even eighteen inches where they form cells and thus pass 

 the winter. Early in May they leave these larval hibernating chambers and 

 return to the roots where they feed a short time and change to pupae the 

 early part of June. The normal larval stage is about ten months. 



