June, '2ll HADLEY: JAPANESE BEETLE 251 



plants as evergreens and azaleas, can only be shipped in this manner. 

 It is obviously impractical to examine such shipments for soil-inhabiting 

 insects with any degree of accuracy, without first removing the soil, 

 a practice which would be injurious if not fatal to the plant. An 

 extensive series of dipping tests is in progress to develop if possible a 

 method of treating such plants for grubs without injury to the plants. 



In dealing with large shippers of the kind of stock just mentioned, 

 any dipping method of treatment would involve so much labor and loss 

 of time as to make such methods impractical on a large scale. An 

 investigation has been commenced to determine the effect of vacuum and 

 pressure on grubs and plants with soil about the roots. A large experi- 

 mental outfit has been acquired, capable of an experimental range up to 

 28 inches of vacuum and 200 lbs. pressure. In general, tests will be 

 planned to determine the mechanical effects of vacutun and pressure on 

 the grub, the effect of toxic solutions on the grub in the soil under 

 vacuum and pressure, and the effect of insoluble gases on the grub in 

 the soil under vacuimi and pressure. 



(3) Investigations to find materials sudable for killing grubs in the 

 Held. The field cyaniding work carried on as part of the control work 

 during the past two seasons has been expensive, and this method is 

 hardly practical for the owner of infested territory to adopt. A series 

 of experiments are now in operation, to endeavor to find a material 

 less expensive than sodium cyanide suitable for this purpose, and to 

 devise a more satisfactory method of applying such materials in the 

 field. 



Parasite Investigations 



Mr. C. P. Clausen is in charge of the parasite investigations in Japan, 

 and although he has been there less than a year, has made substantial 

 progress. At Riverton, a comprehensive investigation of the parasite 

 situation in the infested districts of New Jersey and Pennsylvania is 

 now being inaugurated. A detailed study will be made of possible 

 native parasites or predators attacking the Japansee beetle in any of its 

 stages, and arrangements have been made to bring to Riverton from 

 other parts of this country certain parasites known to attack white 

 grubs of the same relative size as the grub of Popilha japonica. 



In view of the heavy mortality incident to the shipment of living 

 insects from a country as distant as Japan, it seems far more practical 

 to attempt large scale rearing for colonizing here at the laboratory, 

 rather than to depend entirely on material coming from Japan for 

 colonizing purposes. Mr. Clausen is now in a position to ship material 



