214 INTERNATIONAL CONGRESS OF VITICULTURE 



Seasonal History. 



Egg deposition. The females prefer to deposit their eggs in light, sandy 

 soil and our observations indicate that either the females do not oviposit in 

 heavy soil or the eggs (if laid there) do not hatch, for we have never taken 

 larvae from any but the lighter soils. This influence of soil was especially 

 marked in an infested vineyard and hay-land at Westfield, New York, 

 although grapes and grass were on both types of soil on the same farm 

 only the grass roots on the light soil were fed upon by the larvae of the rose 

 chafer. The eggs are deposited near the roots of grass to enable the young 

 larvae to find food in the shortest time. 



The question of the number of eggs laid by a single female has been one 

 that we have tried to answer by means of numerous cage experiments but, 

 with the best of attention, the greatest number laid was 25 while the average 

 was so low that it has no value owing to the large number of cages in which 

 no eggs were produced as well as a number in which only several eggs were 

 laid. Dissections of beetles gave various numbers of eggs ranging from 13 

 to 30 to a female. Dr. Smith secured from females, by dissection, from 24 to 

 36 eggs. For some reason the beetles do not oviposit freely when confined 

 in cages of any practical size. With all care and precautions to secure as 

 near natural conditions as possible, the number of eggs laid was less than 

 would be expected, judging from dissection records. The evidence indicates 

 that the rose chafer does not lay a large number of eggs perhaps 50 is the 

 maximum. 



The depth at which eggs were placed varied from 3 to 6 inches and all 

 were placed singly. The time of egg laying occupies a period of nearly three 

 weeks, the dates for a normal season being from June 25th to July 15th but 

 the finding of copulating beetles as late as July 20th would indicate that they 

 may lay until near August 1st certain seasons. 



Larva. Hatching occurs about two weeks after the eggs are laid and the 

 young grub feeds on the roots of grasses. This feeding is continued until 

 late in the autumn, even a slight breeze seems to be necessary to compel the 

 grubs to seek a lower level and desist from feeding. They dig to a depth of 

 a foot or more to avoid the extreme cold but leave these winter quarters as 

 soon as warm weather appears in the spring, and resume feeding which is 

 continued until the latter part of May. The larvae usually have attained full 

 growth by autumn of the preceding year. 



Pupa. The larvae form cavities in the soil from three to six inches 

 below the surface and here change to pupae. These have been found as 

 early as May 19th but the majority, during a normal season, enter this stage 

 near June 1st. Two weeks is the usual extent of the pupal period but cool 

 weather may retard it to three weeks. Very few larvae are found after 

 June 1st and few pupae after June 20th. 



Emergence. This coincides very closely with the blooming of Concord 

 and Niagara grapes. In 1911 the first beetles appeared nearly a week before 

 these grapes blossomed and it is claimed by growers that one season the 

 beetles did not appear until the grapes were nearly through blossoming. The 

 earliest appearance noted by us was June 3d but the period from June 10th 

 to 20th is the usual time they have emerged. Emergence is more rapid dur- 

 ing the warmer parts of the day. 



