Scientific Agriculture. 



530 



[June, 1912. 



is somewhat similar in form but 

 without the paddles on the hind legs. 



is 



It must not be supposed that these 

 paddle-like organs indicate an acquatic 

 habit. They are merely ornamental and 

 serve no special purpose. 



The young insects resemble the adults, 

 but are smaller and wingless. 



I have not seen the eggs, but judging 

 from the habits of allied species, they 

 are probably deposited in clusters on the 

 twigs and leaves of plants. 



Remedial measures. Sucking insects, 

 that draw their nourishment from below 

 the surface of the plant, are not amenable 

 to treatment by stomach poisons. Any 

 such poison sprayed upon the plant re- 

 mains on the surface and is not absorbed 

 by the insect. Even if it were possible 

 to poison the sap, the remedy would 

 be more harmful than the disease. 



Contact poisons are usually employed 

 against sucking insects, but here again we 

 are met by the difficulty of applying a 

 contact poison sufficiently strong to 

 kill such large creatures, without 

 seriously injuring the foliage and young 

 shoots of the plant. Kerosene Emulsion, 

 Vermisapon, MacDougall's Solution, etc., 

 could be used with safety and effect in 

 the early stages of the insect, while their 

 bodies are comparatively soft and un- 



protected by wing-cases, but the pest is 

 usually not observed until it has arrived 

 at the mature hard-shelled stage, 



Under such conditions the only prac- 

 ticable remedy is to collect and destroy 

 the insects as thoroughly as possible. 

 Every female that is killed may prevent 

 a brood of perhaps fifty young ones. 

 The simplest way to collect them is to 

 beat or shake the branches over a sheet. 

 This should be done very early in the 

 morning or at dusk, when the bugs are 

 comparatively sluggish. In the middle 

 of the day they are very active and, 

 when the branches are disturbed, will 

 take wing and fly off to another tree. 

 Even then they may be caught in rough 

 nets made of mosquito netting or thin 

 cloth, or on bamboo winnowing trays 

 smeared with Car or some other sticky 

 substance. This last is the method 

 commonly employed by the rice culti- 

 vators to catch the ' Paddy bug.' 



I have not had an opportunity of 

 determining whether these particular ' 

 insects are attracted by light. If they 

 are so, the crusade could be continued by 

 night, by exposing small lanterns placed 

 in basins containing kerosene and water. 



Whatever method is employed should 

 be carried out thoroughly and energeti- 

 cally, to ensure the destruction of the 

 bulk of the brood before the insects have 

 desposited their eggs. 



SCIENTIFIC AGRICULTURE. 



THE PRINCIPLES OF THE CIRCU- 

 LATION OF WATER IN TILLED 

 SOILS AND THEIR APPLICATION. 



(Les principes de la circulation de l'eau 

 dans les terrains meubles et leurs 

 applications).— Verhandlungen der zwe- 

 iten Internationalen Agrogeologenkon- 

 ferenz, IV, pp. 117-124. Stockholm, 1911.) 



(Bulletin of the Bureau of Agricultural 

 Intelligence and of Plant- Diseases, 

 3rd Year-Number 3, March, 1912.) 

 According to the writer, the water 

 contained by a tilled soil can be present 

 in the four following conditions : 



1) Capillary Condition.— The water 

 fills all the interstices and further, each 

 soil particle adheres to its neighbour by 

 means of a layer of water which exer- 

 cises a capillary attraction. At the 

 exact point of capillary saturation, the 

 mass of soil and water shows a certain 

 cohesion and the water does not per- 

 colate. 



2) Intermediate Condition.— -When 

 through trituration, the conditions are 

 altered of a soil completely saturated 

 with a quantity of water corresponding 

 to the volume of the spaces between the 

 particles, these spaces increase, and the 



