1923 ENTOMOLOGICAL SOCIETY. 69 



Control 



Cultivation 



It is very evident from what has been said that the importance of cultiva- 

 tion as a means of combating the rose chafer cannot be over-emphasized. We 

 have mentioned that the ovipositing adults are not attracted to cultivated 

 fields to the same extent that they are to uncultivated land, and we have also 

 referred to the fact that land in which cultivated crops such as corn and potatoes 

 are grown, will be free or practically free from larvae and pupae the following 

 spring. We have no information so far relative to the value of fall ploughing 

 or of early spring cultivation, but we do know that the ploughing and cultivating 

 of infested fields during the latter part of May and early June, or in other words, 

 during the period the insect is in the pupal stage, is very fatal to the chafer. 

 The pupae are very readily destroyed by cultivation. Our field observations 

 last spring indicate that all or practically all the pupae which were disturbed 

 by the plough and cultivator died. In eight cage experiments stirring the soil 

 destroyed 100 per cent, of the pupae. 



Spraying 



In 1921 two spray mixtures, viz: (1) arsenate of lead powder three lbs, 

 molasses one gallon, water 40 gallons and (2) self-boiled lime sulphur (8-8-40), 

 were tested in three graperies at Fenwick, the growers making the applications 

 themselves. The sweetened arsenate of lead gave good commercial control on 

 grapes, and was found to be even more effective on sweet cherries. On the 

 other hand self-boiled lime-sulphur proved to be absolutely useless, and where 

 it was applied practically the whole crop was destroyed by the beetles. This 

 was rather surprising in view of the fact that self-boiled lime-sulphur is used 

 for repelling rose chafers in New Jersey. Personally, we could not see that it 

 had any value as a deterrent, as we found the beetles attacking blossom clusters 

 and foliage well coated with spray. 



This year we made a special effort to get all the growers in the affected 

 district to spray their grapes, and our efforts met with a very large measure of 

 success. Several growers expressed themselves as being skeptical about the 

 value of spraying. They informed us that experience had shown them that 

 the chafer "grew fat" on arsenate of lead. However, they were willing to give 

 what we suggested a trial. The spray mixture we recommended and the one 

 which was generally used consisted of four lbs. arsenate of lead powder, one 

 gallon molasses, 40 gallons of water. We increased the dosage of arsenate of 

 lead to four lbs, in order to increase the liability of the beetles consuming a killing 

 dose before they were repelled by the toxic effects of the arsenical. For psy- 

 chological reasons we wanted to make it possible for the grower to readily find 

 dead beetles near his sprayed vines, and we are glad to say that the increased 

 dosage had the desired effect. The growers, even the skeptics, had no trouble 

 in finding fairly large numbers of dead beetles in the sprayed graperies. 



The number of applications given varied from one to four, depending on 

 the severity of the infestation, and on the weather conditions. We had several 

 heavy rains during the chafer season, and this made it necessary in most cases 

 to put on extra applications. In the average season one or two sprays should 

 be sufficient. 



The spray mixture proved very effective in saving the crop of grapes. 

 In twenty-four sprayed graperies the average estimated loss was three per cent., 

 while in seven unsprayed graperies the estimated loss was 84 per cent. 



5 E.S. 



