REPORT OF COMMITTEE ON PUBLICATION 193 



Pupa. The larvae, when ready to pupate, burrow to a depth of several 

 inches and twist their bodies about to form spherical cells in which to trans- 

 form to pupae. The depth of these cells is largely influenced by moisture 

 although there is individual variation in the same soil. The first of these 

 pupae are usually found between June 5th and 10th. This stage lasts for a 

 period of from two to three weeks depending upon the temperature during 

 the period. 



Summary of the Life Cycle. 



The life cycle of the grape root-worm is usually completed in one year 

 although an occasional individual may require two years to complete develop- 

 ment. This may occur because the food supply of the larva has not been 

 sufficient for its needs. The eggs are laid in July and August. These hatch 

 in about two weeks and the young larvae, upon hatching, seek the roots and 

 here feed until fall when they burrow deeper, form winter cells and thus 

 hibernate. They leave these in May and seldom resume feeding. Early in 

 June pupation takes place and the adults emerge the latter part of June. 

 Feeding occurs during July but mating takes place the early part of this 

 month and egg laying is in progress during the latter part of July and early 

 August, although a few eggs may be laid as late as the first of September. 

 The adults begin to die the last of July and by the 15th of August very few 

 are to be found. Rarely they have been found late in September. 



Remedial Measures, 



Efforts to kill the grubs before they enter the soil or after entrance are 

 not regarded as practical owing to the cost. The efforts of entomologists 

 have been directed toward ridding the vineyard of the adults before they 

 have had an opportunity to deposit eggs and to the destruction of the pupae. 

 The first is accomplished by the use of sprays and the latter by cultivation 

 of the soil in such a manner as to destroy the pupae through the breaking 

 of the pupal cells. 



Destruction of the pupae. In New York vineyards it is a common prac- 

 tice to form a low ridge underneath the trellises at the last cultivation of 

 the summer. This ridge is removed, usually during May, after the plowing 

 has been done and it is considered good horticultural practice to remove this 

 early thus avoiding the loss of small roots that might form here were the 

 ridge to remain longer. However, should the grape root-worm be present in 

 serious numbers, the advantage of leaving this ridge undisturbed until the 

 larvae have formed their cells and pupated and then removing it seems to 

 be largely in favor of this latter practice for the deleterious effects to the 

 vine as regards moisture and root injury is more than compensated by the 

 destruction of large numbers of pupae. The average date for this practice 

 is June 10th and the work is done by means of a horse-hoe followed by deep 

 harrowing, preferably with a spring tooth harrow. The ridge serves as a 

 trap for the insects as they are induced to place their cells where they can 

 be reached by cultivation whereas if the ridge be torn away earlier the larvae 

 would form their cells lower and among the roots thus preventing their dis- 

 turbance. The working of the soil breaks the cells and exposes them to the 



