80 DESTRUCTIVE INSECTS OF VICTORIA : 



sort of cave, which prevents the escape of the insects. 

 The locusts are now despatched in tlie trenches by means 

 of glowing embers in places where wood is abundant, or 

 by means of chemicals, such as bisulphide of carbon, 

 creosote oil, or other gas refuse. When these trenches 

 are filled by locusts the first screen is let down, by 

 unfastening the ropes, and the swarm proceeds to 

 encounter a few yards beyond a second series of screens 

 and trenches, or more, according to requirements ; 

 care must, however, be taken not to have the line of 

 screens outflanked by the swarm in motion. This will 

 be done by a little care and practice. The advantage of 

 the screen system over all others being its thorough 

 efficacy, and also its cheapness. Two or three farmers 

 can combine for the purchase of 1,000 or 1,200 yards of 

 screen to cope with small swarms. According to Mr. 

 Koberts, of West Beaufort, in Cape Colony, the cost is 

 about £2 per 100 yards, but doubtless screens made of 

 hessian would be cheaper. (This information is supplied 

 l)y Mr. Peringuey, of Cape Colony, a gentleman who has 

 had a large experience in fighting the locusts in South 

 Africa.) In Algeria and in Cyprus, where labour is 

 cheap— and in the former country black labour is largely 

 available — the screen system is no doubt an admirable 

 one, as is also the system of collecting the eggs, both 

 being preventives, so that the young locusts cannot 

 assume the winged stage, when it is almost impossible to 

 deal effectually with them. Various other measures have 

 been tried with success, one of the best being the cultiva- 

 tion of the castor oil plant (^Bicinifs communis)^ also lark- 

 spur, in belts, across farms, grazing, and orchard areas, 

 as whenever locusts eat these leaves, which they will 

 readily do, the result is always fatal to them. Brush- 

 harrows, chain-harrows, beating, smoking, and other 

 jdans have been tried ; but, judging from the best and most 

 reliable accounts, these have mostly been abandoned in 

 favour of the Cj-prus apparatus, viz., the screen system. 

 Poisoning the food, too, is an excellent plan, which has 



