Vol. XIII. Xn. .iU). 



THE AOIilCULTURAL NEWS. 



235 



i-ateriiillars, with a total fur both staues of about 1,1(IS,0()0; 

 till' iiiiit-ases being some TM per cent, in 1913. This iiicrea.se 

 is not due to a greater abiindaiire of tlie giant moth borers 

 but rather to luueh better work in tlie c pHectiug. 



The writer of the report was fortunate enough to be 

 able to observe the aet of ovipositiou or egg-laying liy 

 a female Vastnia liriis in the field under natural eondition.s, 

 and as this is the first record of this under the.se conditions it 

 is of interest. Briefly stated, the Castnia female alighted on 

 a cane shoot about 1 foot above the ground and worked her 

 way r,i])idly backward down to the base, forcing the tip of 

 the abtlomen between the cla.sping base of a dry leaf and the 

 cane .stalk and deposited an egg there. The egg was obtained 

 and it hatched in fourteen days. 



The l>elief is expre.s.sed that it is nece.ss.iry to pn>h \ igo- 

 ronsly the continued collection of the moths and cuterpillars 

 of tlii.- insect anti that this will reduce the nuniber> to a point 

 where it will l)e able to inflict only a miniinum of damage 

 and will keep it there. 



WKEVIL BOIiKK Il.Vltll B.\(KS AM> .ME.\LV-Bl'i;. 



The weevil borer (Metamasius /lemipteni^) wasabumlant 

 at certain sea.sons and on certain estates. The .severest attacks 

 appear to come on as a rule during the mid-year rainy 

 months. On some e.states the damage resulting from the 

 attacks of the weevil borer was greater than that from those 

 of Cahtniii liens, although it is not usually con.sidered a .serious 

 ])est. The number of adults and larvae of the weevil borer 

 collected during the vear on si.x estates was reported as 

 1,952,480. 



The palm weevil {Rliijnchophorv!, palmarum) the larva 

 of which is the grn-gru worm, was observed on one e.state in 

 small numbers. The hard back beetles were not of nnicli 

 importance during the year under review. 



The pink mealy-bug {Pseiirfncoa-us calce<ilaruie\ the 

 sugar-cane Aspidiotus {AspvHntus sacc/iaii), Orthezia insii/nif, 

 and a species of I'ulvinaria are mentioned as having occurred, 

 the mealy-bug being the only one that was aliundant. 



FEOonopi-KR {Tnmafpis Jlavilittra). 



During the long and serious drought of 1912 the frog- 

 hopper almost completely disappeared, but in the more normal 

 weather of 1913 it again made its appearance. Where 

 obser\ed, the fioghojipers were feeding less on the cane roots 

 than on the grass root.s near the drains. They were not at 

 any time during the year so abundant as to cause any alarm, 

 but on account of the serious attack of the related species, 

 Tovmspis varia, in Trinidad, it is realized that this insect 

 sIk.uIiI be regarded with suspicion and watched with care. 

 The cane stool moth, Acrolop/iHS sacc/iari, was not very 

 abundant. 



The grasshfippers, Cimnceplt'iloidiS i/ta.rillosus and Sc/ii-f- 

 tocerca pallens, were generally present, but not in destructive 

 nuniliers. Several leaf-feeding caterpillars of mirths and 

 butterflies are recorded of which only two, the grass looper 

 (Rer.ii'iia repauda), and the corn ear worm \Laphy<iina 

 fnif/iperda) were of any importance during the year. 



One of the interesting results wliich is likely to become 

 \'ery useful from such work as that recorded in the report 

 under review is the accumulation of information in regard to 

 the natural enemies fif in.sect pe.sts. This information is most 

 likely to be obtained in work which involves the handling 

 and inspection of large numbers of insect pe.sts in their 

 different stages of growth. In the rejiort under review there 

 are records of parasites and predators attacking certain pestn, 

 and in certain instances iid'orniation relating to habits and to 

 secondary parasites. Sncli information accumulates slowly 

 )>ut with each addition liecomes more valuable. 



AGRICULTURAL ENGINEERING, 



LECTURES ON EXPLOSIVES. 



A recent publication of the Institute of Chemistry of 

 Great Britain and Ireland, having the above title, may lie of 

 some general interest to agricultural scientists who are con- 

 ducting trials with e.xplosives for the purpo.se of improving 

 soil conditions. The greater part of the information contained 

 in the lectures is industrial and deals principally with the 

 manufacture of e.xplosives: but there are certain parts, as for 

 example, tliose treating of the temperature and volume of the 

 gaseous products of explosions which are of interest in 

 relation to the effect of these phenomena on the soil. Agri- 

 culturally it would be interesting to know more about the 

 effect of the ga.ses produced in the soil as the result of the 

 exjjlosion of dynamite. It seems that carbon dioxide, carbon 

 monoxide, hydrogen and nitrogen are the principal gases 

 formed where there is insufMcient oxygen for complete oxida- 

 tion. It is stated in the publication that when an explosive 

 is fired in a closed vessel under different densities of charge, 

 that is, different (ptantities of explosives in the same volume, 

 the volume and composition of the gas vary with the 

 pressure developed with the explosion, the cartion dioxide 

 and hydrogen increase, and the carbon monoxide in water 

 diminishes as the pressure increases; at high pressures, con- 

 siderable amounts of methane are formed. Carbon monoxide, 

 unlike carbon dioxide, is an active poison, and it is worth 

 considering what the effects of this gas are after its production 

 by explosive changes in the soil. 



The temijerature developed by an explosive is of 

 importance, and tJie following formula t = -2 where q = the 



calories set free and c = the mean specific heat of the gases, 

 should give the theoretical temperature developed by an 

 e.xplosive. 



New Soil- Tiller.— Tlie Times, in its issue for the 

 8tli in>tant, describe^ atrial which has just taken place in 

 Kent, near Farningham, of a new rotary soil-tilling machine, 

 which conil lines the action of plough, cultivator and harrow 

 all in one. The action of the machine resemlsles that of 

 a i)otato digger, except for being backwards instead of 

 transverse, and it leaves the land in an open, loose condi- 

 tion very favourable to subsequent cultivation. It is driven 

 by a 30-h.p. petrol engine, and the largest of the three sizes 

 in whicli it is obtainable weighs 2 tons. The cost is about 

 £+00, the irther sizes being about £300 and £100 respect- 

 ively, and the three widths are 7 feet, 5 feet, and 3 feet. 

 Thf machine is capable of cultivating to a depth of from 

 2 inches to 12 inches; it can tackle hard land as easily as 

 soft, the <jnly difference lieing that of speed, which varies from 

 1 foot to 3 feet per second. The total cost of the operation 

 varies from 12s. to 18s. per acre, and the effect considerably 

 exceeds that at present obtained by implements already in u.se. 

 {Gardeners Ghronich, June 13, 1914.) 



It is stated in The Board of Trade Journal for June 4, 

 1914, that a motor tractor made in England has just passed 

 successfully through searching tests in Siam, and is likely to 

 prove useful in actual practice. The machine is of 20 h.p. 

 with a drawback pull of 2,750 fc., and is capable of 

 hauling a waggon with a load of 4 tons. The tractor and 

 waggon travelled successfully over rough ground, through 

 a liig heaj) of burnt paddy ash, and finally climl)ed lianks over 

 2 feet high. This machine may lead to the successful intro- 

 duction of a motor plough suited to local conditions. 



