384 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



spray mixtures and apparatus, with the view of reducing cost of 

 treatments. It has been found that the period for most effective con- 

 trol varies considerably with the locality and the species, and that 

 recommendations must be based on seasonal development of the 

 species concerned. Results are now being obtained as to the value of 

 dusting for the control of grape leafhoppers, but further observa- 

 tions will be necessary before final conclusions are warranted. 

 Studies of the hibernating habits of the three-banded leafhopper 

 indicate that a large proportion of the adults remain in the vineyards 

 over winter and congregate on various plants, as dandelions, before 

 grape foliage appears in the spring. Preliminary tests show that 

 a large number of these can be destroyed by the application of proper 

 contact sprays or by other methods. Further information is being 

 secured on the rose chafer, a serious pest of grapes in certain parts 

 of the Ohio and Chautauqua-Erie grape belts. The grape-berry 

 moth continues to cause important injury in some vineyards, and 

 experimental work in its control is under way. It has been deter- 

 mined that where previous spraying has been thorough in vineyards 

 control of the berry moth can be secured by a single spraj^ application 

 made about July 10. At this time the use of a combination spray 

 will also be effective against the grape rootworm and grape leaf- 

 hoppers. 



At the Fresno, Calif., station special attention has been given to 

 determining the value in the control of the grape Phylloxera of 

 paradichlorobenzene. Unfortunately the results secured indicate 

 that this chemical can not be used with success against this insect. 



The Achemon sphinx again appeared in large numbers in vine- 

 yards at Madera and Livingston during the summer of 1922, and 

 further experiments were made in testing remedies for its control. 

 A report of these experiments was issued in the January-February 

 number of the Monthly Bulletin of the California State Depart- 

 ment of Agriculture. Work on the grape mealybug under way at 

 this laboratory for some seasons has been much reduced, owing to 

 the fact that this insect is now being controlled effectively by 

 parasites. 



Nut insects.— Investigations of nut insects have been continued 

 as heretofore. Northern nut insects have been studied at the French 

 Creek, W. Va., station and pecan insects at Brownwood, Tex. Dur- 

 ing the spring of 1923 an additional laboratory for the investigation 

 of pecan insects was established at Thomasville, Ga., in view of the 

 serious depredations to pecans of certain pests in the Southeast. 



At the West Virginia station particular attention has been given 

 to weevils attacking chestnuts and other nuts grown in the northern 

 United States. In cooperation with the Bureau of Plant Industry, 

 experiments are under way to determine possible practical methods 

 of control of chestnut weevils, including spraying with arsenicals. 

 Biologic studies of the so-called cambium curculio, G onotrachelus 

 anaglypticus^ have been completed and a manuscript prepared for 

 publication. This insect, often mistaken for the plum curculio, 

 occurs frequently on peach, to which it does some injury. It is more 

 particularly injurious by mining around wounds in the bark of many 

 kinds of trees, thereby enlarging and preventing the healing of the 

 injury. Investigations at this station are also being made of certain 



