400 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



destroyed and it is likely that under the vigorous system of inspec- 

 tion and treatment practiced in Mississippi no camphor scale now 

 exists in that State. 



Special work is being done to develop efficient and economical 

 sprays for the control of the camphor scale on its various host 

 plants. Many tests have been made to ascertain the proper strength 

 of and exposure to hydrocj^anic-acid gas for the disinfection of 

 nursery stock shipped out of the New Orleans area. All regulatory 

 and other work designed to prevent the spread of this pest is in the 

 hands of the officials of the various States interested. Special at- 

 tention is being given to this work by the Louisiana State entomolo- 

 gist in view of the general occurrence of the pest in New Orleans 

 and the amount of florist and nursery stock being shipped out. 



Greenhouse insects. — The studies of greenhouse insects under 

 way for some years have been continued and enlarged to meet the 

 demand for information from florists and others concerning insects 

 attacking plants grown under glass. The investigation of the 

 strawberry rootworm, an insect injurious to roses, has been com- 

 pleted and a satisfactory method of control determined, which has 

 been published in Farmers' Bulletin 1344. The insects attacking 

 chrysanthemums have been studied and a publication giving advice 

 on this subject distributed during the spring. Experiments in the 

 control of Ghrysomphalus aonidum on Kentia, Phoenix, sago palm, 

 and rubber have been carried out, and it has been found that fumi- 

 gation, using 1 ounce of sodium cyanid per 1,000 cubic feet of 

 space, will give 100 per cent control without injury to the plants, 

 provided the plants are properly shaded before and after fumigation. 

 Tests of many different insecticides on this scale have been made, 

 with the result that lubricating-oil emulsion has proved to be very 

 satisfactory for its control, producing a mortality of 78 per cent. 

 A second treatment with the emulsion however gives a control of 

 approximately 100 per cent. Numerous other important studies 

 are in progress, as experiments in the fumigation of Dutch bulbs; 

 tolerance of plants to hydrocyanic-acid gas; control of earthworms 

 with contact insecticides ; liquid cyanid experiments, etc. 



VEGETABLE AND TRUCK-CROP INSECT INVESTIGATIONS. 



Work on the project of vegetable and truck-crop insects has been 

 continued as formerly under the direction of Dr. F. H. Chittenden. 

 The Mexican bean beetle and the sweet-potato weevil have been the 

 subjects of special lines of investigation, the former with a view to 

 the discovery of an insecticide which will effectively destroy the insect 

 without at the same time injuring beans and other leguminous crops 

 affected, the latter with special reference to its eradication in Mis- 

 sissippi, Alabama, Georgia, and certain sections of Florida. 



The Mexican bean bettle. — The Mexican bean beetle has con- 

 tinued to extend its northward range. A slight extension was noted 

 in Georgia in the counties southeast of Atlanta. The Thomasville 

 infestation has apparently not changed. "Wliile it is hoped that such 

 conditions as low altitudes, warm weather, and the absence of moun- 

 tains are unfavorable for the development of this pest, it is still too 

 early to draw definite conclusions. The extension of infested territory 

 includes two new States — Mississippi (one county) and Virginia (two 



