GRAPE INSECTS 



447 



clusters, averaging 25 to 40 eggs each The ])eetles normally 

 begin to lay eggs the second week in July, and oviposition is at its 

 height the latter part of the month, but eggs are deposited by 

 a few belated individuals uj) to tlie first of September. The 

 eggs hatch in from eight days to two weeks, depending on the 

 temperature ; in the latter part of the season incu])ati()n may 

 last for over three weeks. Eggs laid after the first of September 

 do not, as a rule, hatch. 



On hatching the young grub drops to the ground and, taking 

 advantage of any crack or crevice in the soil, soon burrows down 

 to the roots of the 

 vine. Here it feeds 

 for the rest of the 

 season on the finer 

 roots, and when 

 these are consumed 

 attacks the larger 

 roots and the un- 

 derground part of 

 the stem, eating out 

 burrows and pits in 

 the bark, as shown 

 in Figure 389. 



A few of the- 

 grubs complete their growth (Fig. 386) the same season, 

 but the majority are only about three fourths grown at the 

 time for going into hibernation in October and November. 

 Towards the last of May and in June the grubs ascend to within 

 two or three inches of the surface and there construct earthen 

 cells within which about three weeks later they transform to 

 whitish or pinkish-white pupae (Figs. 387 and 388). On an 

 average, 17 days are spent in this stage. After transformation 

 the beetles remain in the pupal cell for several days, in order to 

 become hardened, and then burrow to the surface, emerging to- 



FiG. 388. — Grape root-worm pupa in its earthen cell. 



