August 17, 191 1] 



NATURE 



in stored cereal products, and may become serious pests 

 if they succeed in establishing themselves. Two other 

 pests infesting stored cereal products are also described, 

 the lesser grain-borer (Rhizopertha dominica, Fab.), which 

 is fairly common, and is cosmopolitan in its distribution, 

 and the larger grain-borer (Dinoderus truncatus, Horn), 

 which is more confined to tropical countries. The ravages 

 of the codling moth {Carpocapsa pomonella, L.) in Cali- 

 fornia are dealt with by S. W. Foster ; two full broods 

 of larvce could be traced during the season, the first, how- 

 ever, being relatively small, and often overlooked. Treat- 

 ment with a lead arsenate spray is recommended. The 

 grape leaf-hopper (Typhlocyba comes, Say) an insect 

 causing damage to vines in the Lake Erie Valley, is shown 

 by F. Johnson to yield to a nicotine spray. Three pests 

 on crops are dealt w-ith : the timothy stem-borer 

 Mfordellistena ustulata, Lee), a pest which has recently 

 been observed by \V. J. Phillips; the sorghum midge 

 Kontarinia sorghicola, Coq.), described by W. H. Dean ; 

 and the maize billbug (Sphenophorus maidis, Chittn.), by 

 E. O. G. Kelly. The alfalfa caterpillar (Eurymus eury- 

 Lme, Boisd.) is dealt with by V. L. Wildermuth ; it is 

 very common, and does a good deal of damage in various 

 localities. A very useful bulletin by L. O. Howard sets 

 out various remedies against mosquitoes. The best 

 mixture for keeping them off was found to be i part of 

 oil of citronella, i of spirit of camphor, and J of oil of 

 cedar ; a few drops sprinkled on a towel and hung over 

 the bed will keep mosquitoes away during the night. For 

 the actual bite the most satisfactory remedy is said to be 

 moist soap. Traps are described, and methods for the 

 destruction of the insects over both large and small areas 

 are set out. 



Hydrocyanic acid has long been recognised as one of 

 the most potent fumigating agents, but great practical 

 difficulties are met with in its use, which so far have 

 not been entirely overcome. If the concentration of the 

 acid is too high the tree is killed, if too low some of the 

 insects escape ; further, the optimum concentration depends 

 somewhat on the conditions. Thus there is almost an 

 indefinite field of work for entomologists, and a stream of 

 bulletins is issued on this subject. Among recent issues 

 from the United States Bureau of Entomology are two by 

 R. S. YVoglum and one by C. C. McDonnell. 



The work of the West Indian Department of Agriculture 

 is published in the West Indian Bulletin, but summaries 

 are also given in The Agricultural News, the fortnightly 

 organ of the Department. In vol. xi., No. 2, of the 

 bulletin H. A. Ballou gives a list of the insect pests 

 prevalent during 1909-10, a corresponding list of the 

 fungoid pests being prepared by F. W. South. This is the 

 first occasion on which information of this nature has been 

 collected, and it is proposed to repeat the reports each 

 year in order to obtain some records of the increase or 

 decrease of any given pests, and thus to determine the 

 effectiveness of the preventive measures used for control. 

 The value of such a plan is obvious, and it might with 

 advantage be adopted in our own country. 



Considerable interest attaches to the control of insect 

 pests by natural parasites, and we note that in Barbados 

 the hymenopterous parasite Zalophothrix mirum. Craw., 

 was able to keep in check the black scale insect (Saissetia 

 nigra. Nietn.), whilst in St. Vincent it was not so 

 effective. Simple instructions are given in issues of The 

 Agricultural News showing how planters may introduce 

 the parasite among the insects, and thus increase its 

 action ; in No. 232, in particular, a summary of the whole 

 subject is given. Active search for parasites of other pests 

 is in progress by other departments : investigators were, 

 for instance, recently sent from the United States to 

 Panama to search for parasites of the citrus white-fly 

 (Aleyrodes citri), of the cotton boll-weevil, and allied 

 species. 



A w ll-illustrated bulletin has recently h°en issued by 

 P. L. Guppy on the life-history and control of the cacao 

 beetle (Steinastoma depression, L.), which for some vears 

 past has been a serious pest and a source of trouble to 

 glanters in Trinidad. Hitherto nothing definite seems to 

 have lven worked out in regard to its life-history, and its 

 babits have only been superficially observed. Mr. Guppy's 

 publication supplies much useful information on the insert. 



NO. 2 1 8l, VOL. 8/] 



WATER SUPPLY. 1 



"T""HE question of water supply is in one aspect a scientific 

 one, and in another aspect a political one. The 

 source of all water supply is evaporation, which raises and 

 purifies water which is taken up from the land and the 

 sea, which after condensation is returned to us as rain, 

 dew, snow and hoar frost, and these waters are to be 

 found ready to our hand in springs, streams, lakes, and in 

 the envelope of earth which is tapped by means of wells. 

 In early days the water supply was a matter of hand to 

 mouth. In the matter of water, at any rate, men drank 

 water when they were thirsty — unlike the characters in 

 Maeterlinck's " Palace of Happiness," who had, you will 

 remember, the Luxury of Drinking when they were not 

 Thirsty and of Eating when they were not Hungry. In the 

 old days people, in relation to these ordinary articles of 

 diet, acted upon the advice given in that old-world book 

 " Sandford and Merton," and " only drank when they were 

 drv." Yet even in the old days men in this country used 

 water occasionally for washing, although the modern 

 passion for baths had not developed in the dark ages. We 

 find, however, that even in these early days there was a 

 political aspect in water supply. The existence of springs 

 in many cases determined the sites of cities. Many towns 

 have been built on rivers partly because they were sources 

 of water supply, but mostly when the rivers were navigable 

 and afforded a highway for ships. Now, however, it is 

 found that populations have increased to such an extent in 

 certain localities, owing to the gregariousness of men and 

 other political considerations, that the immediate sources 

 have proved inadequate, and great towns in this country — ■ 

 like Rome in ancient days — have had to go a distance for 

 their water supplies, and have had to construct great 

 engineering works for the conveyance of water to the area 

 of distribution. Water is at present collected and sold in 

 England to a value of nearly S.ooo.oooZ. annually, and 

 when it is delivered at the house of the consumer it costs 

 him about 2d. a ton. 



Aqueducts, or channels by which water is conveyed along 

 an inclined rilane, were known to the Greeks, but there are 

 no remains of those they constructed. The Roman aque- 

 ducts were amongst the most important of their great 

 works, and the present supply of Rome is still carried by 

 these artificial rivers, sometimes through passages cut in 

 the hills, sometimes on arches bridging the valleys and 

 carrying the" water across the plains. One of these aque- 

 ducts is 62 miles in length. We in this country have had 

 to go even further afield for our water sources. A larjje 

 portion (56 per cent.) of the supply of Liverpool is brought 

 from the River Vyrnwv, in North Wales, a distance of 

 fiS miles. Leicester is 60 miles from the sources of the 

 Derwent Valley Water Board supply ; Birmingham gets its 

 water from Radnorshire, a distance of 74 miles ; and 

 Manchester from Thirlmere. by means of pipes and aque- 

 ducts, a distance of 96 miles. Paris derives some of its 

 water from the Champagne district through pipes and 

 aqueducts 80 miles in length, and some from Vanne,_ a 

 distance of 104 miles. There has, too. been a suggestion 

 that London should draw its public water supplies from 

 Wales, which would involve carrying the water about loo 

 miles. This scheme was first suggested by Mr. Bateman 

 in 1S67. He proposed to collect the rainfall on 204 square 

 miles, and, by means of an aqueduct 17;, miles in length, 

 to bring 230 million gallons of water a day to London, and 

 he estimated the cost at 11,400,023!. About the same time, 

 too, there was a suggestion to carry the water of Ulls- 

 water and Hawswater, which it was said could supply 

 530 million gallons a day from an area of 100 square miles 

 to the metropolis, supplying Liverpool, Leeds, Bolton, 

 Bury, Blackburn, Huddersfield. &c, on the way. These 

 great ideas were, of course, too large to be realised in these 

 small times, and many of these towns have, since the 

 suggestion was made, supplied themselves with water by 

 means of comparatively small scale _ works instead of 

 becoming parties in a national undertaking. 



The difficulty of meeting the demands of such large tow — 



- livious. from the fact that it involves such great works 

 and such heavy expense to secure an adequate supply. 



' From a discourse delivered at the Royal Institution on Friday. March 17, 

 l,y J. H. Balfour Browne, K.C. 



