385 



what appeared to be a waiting position. When a hair from a camel's 

 hair brush was brought into contact with them, it was immediately 

 grasped and the mite loosened its hold on the leaf-hair and allowed 

 itself to be carried away. A mite could thus easily attach itself to an 

 insect or bird. Early in 1916 a few cotton seeds were brought to 

 Barbados from another island and planted in concrete tanks covered 

 with cages of fine mesh wire. No cotton had been grown in these 

 previously and no cotton is grown in the district. The first leaves of 

 the plants from these seeds showed the characteristic signs of leaf- 

 blister mite attack and there seems to be no possibility that the mites 

 could have found their way to these plants except on the seed. The 

 disinfection of all cotton seed used for planting in a solution of one part 

 corrosive sublimate to 1,000 parts water is therefore recommended. 



Runner (G. A.). Effect of Rontgen Rays on the Tobacco or Cigarette 

 Beetle and the Results of Experiments with a New Form of 

 Rontgen Tube. — Jl. Agric. Research, Washington, D.C., vi, no. 11, 

 12th June 1916, pp. 383-388. 

 Under laboratory conditions tests made with a Rontgen-ray tube 

 permitting a high-energy input and giving an intense and powerful 

 radiation gave results which promise that the X-ray process may be 

 successfully used in the treatment of cigars or tobacco infested with the 

 cigarette beetle [Lasioderma serricorne]. In treating the egg-stage, 

 heavier exposures are required to sterihse eggs which are near the 

 hatching point than newly laid ones. A dosage equivalent to 150 

 milliampere minutes exposure with a spark gap of 5 '5 inches gave 

 satisfactory results with eggs in tobacco placed 7*5 inches from the 

 focal spot of the tube. With this exposure the eggs in which embryonic 

 development was well advanced hatched, but in all cases where these 

 larvae were kept under observation, they failed to reach the adult 

 stage. In two separate experiments adults were given an exposure 

 of 600 milhampere minutes, -^dth a spark gap of 5*5 inches, giving an 

 approximate voltage of 65,000, with humidity at 57. The distance 

 from the focal spot of the Rontgen tube was 7*5 inches. No effect 

 on the length of life was apparent, as the beetles died at about the same 

 rate as the same number of beetles kept as a control. Large numbers 

 of eggs were deposited after exposure, but were infertile, though eggs 

 from the control beetles hatched normally. Larvae were given an 

 exposure of 600 milliampere minutes, other conditions of the experi- 

 ment being the same as with the adults. While no immediate effect 

 was apparent, the treatment had the effect of stopping activity and 

 development, the larvae remaining in a dormant condition for a pro- 

 longed period. All treated larvae died before reaching the pupal 

 stage. 



Rand (F. V.) & Enlows (Ella M.A.). Transmission and Control of 

 Bacterial Wilt of Cucurbits. — Jl. Agric. Research, Washington, DC, 

 vi, no. 11, 12th June 1916, pp. 417-434, 2 plates, 3 figs. 



In the experiments so far completed, the cucumber beetles, 

 Diabrotica vittata, F., and D. duodecim punctata, L., have been shown 

 to be the most important, if not the only summer carriers of the wilt 

 organism, Bacillus tracheiphilus [see this Revieiv, Ser. A, iv, pp. 27 and 



(C294) B 



