76 



The most effective season of application will probably be found to 

 be at about the time when the weevils are doing their maximum 

 injury to the crop and the cotton manifestly slackens in blooming, 

 once a week probably constituting an eiTective application. Much 

 more effective poisoning with dry dust can be conducted while the dew 

 is on the plant, and it will probably be found advisable to poison 

 as much as possible during the evening, night, and early morning, and 

 to do so during the day only in case of emergency. 



Hitherto the amount of poison needed for an application has 

 depended on the requirements of the machinery used rather than on 

 the amount necessary to dust the plants thoroughly. The experimental 

 average of 5 lb. per acre is obviously excessive, and with improved 

 machinery effective poisoning may be accomplished with a much 

 smaller amount. The number of applications will of necessity vary 

 with the size of the plot to be dusted, a single application over a large 

 area being as effective as three on a small one, in consequence of the 

 constant migration of further weevils into the latter. 



The cost of treatment varies widely ; in experimental work it has 

 averaged about 4 shillings an acre for each application. With improved 

 machinery and the use of carriers this can be much reduced, and a 

 further economy may be effected by giving several apphcations to 

 that part of a plantation near the hibernation quarters of the pest 

 before the weevils have become sufficiently abundant to start move- 

 ment, the remainder needing perhaps only a single application. A 

 definite plan of procedure for the poisoning of weevils under all con- 

 ditions is impossible at the present stage of the investigation and much 

 more experimental work will be needed before such a plan can be 

 proposed. 



McAtee (W. L.). Notes on Nova Scotian Eupteryid Leaf-hoppers 

 including Descriptions of Two New Species.— Cowaf^tan Entomo- 

 logist, London, Ont., 1, no. 11, November 1918, pp. 360-361. 



The new species here described are Typhlocyba cymha, and 

 Erythroneura odor from specimens on elm. 



Sasscer (E. R.) & Sanford (H. L.). Effect of Hydrocyanic-acid Gas 

 under Vacuum Conditions on Subterranean Larvae. — Jl Agric. 



Research, Washington, DC, xv, no. 3, 21st October 1918, 

 pp. 133-136. [Received 18th December 1918.] 



Under normal conditions from five to seven million ornamental 

 plants are introduced into the United States annually with balls of 

 earth round their roots, without the removal of which it is impossible 

 satisfactorily to inspect and safeguard the plants. Since practical 

 horticulturists strongly advise against this course, experiments have 

 been made to test the fumigating power of hydrocyanic-acid gas under 

 vacuum condition^. Larvae of Agriotes niancus, Say (wheat wire- 

 worm), AllorrhirM (Cotinus) nitida, L. (green June beetle), Lachnosierna 

 (white grub), and Popillia japonica, Newm., were exposed to the gas 

 in potting soil, dry, moist, and soaked, in 3-inch flower pots, the larvae 

 being from 1 to 3 inches from the surface of the soil. The chemicals 

 used were sodium cyanide guaranteed to contain not less than 51 per 



