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or even 1 later, or when spraying was done at night. The deadly 

 action of the emulsion is attributed to the phenols and cresols con- 

 tained in the heavy tar-oil, which have a reducing action and penetrate 

 into the spiracles of the locusts. The effect is deadlier and more rapid 

 in proportion to the violence and suddenness of the spray, from which 

 the author believes that the locusts keep their spiracles open when at 

 rest and close them on being disturbed. Dr. Alfredo Parozzani 

 believes that besides carbolic acid and its analogues, other bodies 

 existing in the tar-oil, such as naphthols, pyridine bases, etc., act 

 upon the locusts. The soap renders the body of the insect more 

 sensible to the caustic action of the emulsion. Portable sprayers were 

 used and as rubber hose swells and cracks, oil-cloth hose is required. 

 This new system does not present any danger ; it is as efficient as 

 the petroleum flame, perhaps more so, and costs less than any other 

 means of control ; for while with 22 gals, of benzine-petroleum, 

 costing about £2, 2,770 to 3,770 square feet of ground covered with 

 locusts can be burned, the same quantity of emulsion for locusts in 

 their first stages costs only about 2s. 2d. and will spray 2,150 to 3,220 

 feet. The emulsions used later, cost respectively 2s. 8d. ; 3s. 2d. ; 

 3s. 7d. ; and 4s. 4d. per 22 gals. As the locust eggs deposited in one 

 locality do not all hatch at once (sometimes at considerable in- 

 tervals, if the weather be unfavourable) the necessity of revisiting, 

 and perhaps of treating again the areas which have already been 

 scorched or sprayed, is apparent. To avoid this, the soil, if not stony 

 or hard, may be hoed to a depth of a couple of inches and the loosened 

 soil collected in heaps and every layer rammed with a heavy rammer ; 

 only a few of the egg-masses will escape destruction and hatch out. 

 Night work by artificial hght gave very good results w^ith the emulsion. 

 Sheets are very effective in collecting locusts and a useful modification 

 of them is described. This collector consists of a zinc hopper carried 

 on a light vertical frame to the base of which is fixed a horizontal 

 frame laid on the ground. A sheet is stretched between two rollers, 

 one being at the top edge of the vertical frame and the other at the 

 free front edge of the horizontal frame on the ground. The locusts 

 which get on to the inchned sheet, fall into the hopper, when the latter 

 is wound up. The collection of egg-masses is recommended as an 

 additional means of control where infestation is severe. From 26th 

 Octo])er 1913 to 30th March 1914, nearly 100 tons of locusts' eggs were 

 collected under the author's direction. They represented 6,500 

 milhons of insects and the total cost was £1,240, an average of l-38d. 

 per lb., containing about 29,000 eggs. Collection costing over 2|c?. 

 per lb. will probably not pay. According to experiments, which, 

 on account of their nature, cannot ahvays yield the same figures, the 

 destruction of 1,000,000 locusts costs from 12s. Qd. to 25^. when 

 petroleum is used ; 16s. to 32s. with the sheets and Is. 8d. to 5s. lOd. 

 with the emulsion. Picking the eggs may cost from 4s. 2d. to 25s. 

 and upwards per 1,000,000. It is estimated that from 16th April 

 to 11th July 1914, in Catania, about 1,185 acres of land covered with 

 locusts were sprayed with emulsion, about 880,000 lb. of locusts, of 

 all sizes, being destroyed. With the sheets, 198,000 lb. of locusts in 

 the nymph and winged stages were collected. From these approximate 

 calculations, it is estimated that about 12,000 million lociists were 

 destroyed at a cost of £1,440. 

 (CISS) a2 



