Vol. VIII. No. 179. 



THE AGRICULTURAL NEWS. 



75 



.cage with some healtliy cotton worm larvae and pupae, and 

 into the same cage were put s|)ecimens of Sjnroc/i'i/ns, with 

 the idea that if the Sarcophagidae attacked the cotton worm 

 pupae, the Spivochak-ia would, in turn, attack the Sarcopha- 

 gid cocoons. As the Sarcophagid Hies did not attack the 

 cotton worms, there were no positive results from the experi- 

 ments. This trial, however, aeems to .strengthen the belief 

 that the Sarcophagid flies only attack pupae which are 

 already damaged. On the other hand, it is difficult to under- 

 stand how it happens that so many pupae get damaged, as to 

 account for the large number of Sarcophagid cocoons which 

 .are found on them. 



Experiments with a Sarcophagid fly (Sarcoj//ti(i/a trudt- 

 tata) were made at the laboratory of the Imperial 

 Department of Agriculture some time ago, as follows : 

 Tupae of the cotton worm v,-ere collected in the field and put 





Fk;. 12. A Sarcoi'iiagiu Fly. 



(Sdicdjjliaga sarureiiia. ) 



Actual length indicated by hair line. Redrawn, after Wash- 

 bum, from Willi.ston's Manual nf N. A. Diptera, p. 348. 



into a box covered with muslin. Four days later there were 

 136 moths in the box. These were put into a large glass jar, 

 which was also covered with muslin. Thirteen days after the 

 moths were put into the jar, five flies {Sarrop/iai/d trioittata) 

 also apijeared in the jar. The eggs from which these flies 

 developed must have been deposited on or in the larvae or 

 pupae of the cotton worm in the field, and these latter wexe 

 not sufticiently injured to prevent their completing their life 

 cycle and emerging as moths. It seems more likely that, in 

 this case, the parent flies attacked the healthy cotton worm 

 larvae or pupae, and that in .spite of the effect of this attack, 

 the latter were able to complete their development. 



Further information in regard to the parasites of 

 the cotton worm and other pests attacking agricultttral 

 ■crops is most desirable. Readers of the Agrlcaltaral 

 Ne^t's are asked to be on the look out for parasitic and 

 predaceoiis insects of all kind.s. The Imperial Depart- 

 ment of Agriculture will always be glad to have 

 observations and specimens Irum an3'one who will send 

 them in. Directions for collecting and forwarding 

 specimens of this sort will appear in the Aijricnltii ral 

 Jietus in the near future. 



RECIPE FOR WHITEWASH. 



The Journdl of .the .Jamaica Agricultural Society 

 gives the following recipi' for preparing a whitewash, 

 which it describes as 'one that will not rub off': — 



A first-class wOiitewa.^h is made by dissolving 2 lb. of 

 ordinary glue in 7 pints of water and when all is dissolved, 

 adding 6 oz. of bichruniate of potassium, dissolved in 

 a pint of hot water. Stir the mixture up well, and then add 

 sufficient whiting to make it up to the usual consistency, and 

 apply with a brush in the ordinary manner as quickly as 

 possible. This dries in a very short time, and by the action 

 of light becomes converted into a perfectly insoluble water- 

 proof sulistance which does not wash off' even with hot water, 

 and at the .same time does not give ri.se to mould growth, as 

 whitewash made uj) with size often does. It may lie coloured 

 to any desirable shade liy the u.se of a tr-ice of any aniline 

 dye or ]iovvdered colouring, while by the addition of a small 

 proportion of calcium sulphite, its anti.septic power is much 

 increa.sed. 



SOME NOTES ON CALCIUM CYANAMIDE. 



The method of manufacturing calcium cyanainide, 

 a new nitrogenous inmure, the nitrogen of which 

 is derived directly frorn the air, was described in the 

 Agrirnlturiil iVcuw of December 12 last (page 398). 

 In this connexion it is interesting to note some experi- 

 mental work lately carried out by two French investi- 

 gators with this manure, and reported on in the 

 Airiuiles <Je Vliisiitut Nationale Agronomiqae. 



Before calcium cyanamide can be utilized by plants, it 

 is first transformed into ammonia, and then into nitrate of 

 soda. These changes, uuiler favourable circumstances, are 

 fairly rapidly efl\;cted by means of soil bacteria. Nitrifica- 

 tion is especially rapid when the manure is applied only in 

 small quantities at once. Very large quantities of the 

 cyanamide applied at one time, appear to paralyse the activi- 

 ties of the nitrifying bacteria, with the result that trans- 

 formation into nitrate of soda is considerably delayed. 

 Experiments carried out by the French investigators men- 

 tioned, .showed that the retarding action was due to the influ- 

 ence of the cyanamide itself rather than to the caustic lime 

 which accompanies it, and further, that although the manure 

 should always be used witli prudence, yet soils rich in organic 

 matter can advantageously take up more of the manure than 

 soils deficient in this constituent. The toxic effect which the 

 manure undoubtedly exercises on the living organisms of the 

 soil when used in large amount is reduced to a negligible 

 quantity when employed in moderate doses. 



Nitrogen does not appear to be readily lost from 

 cyanamide on storage. When kept in sacks, and stored in 

 a dry place, there was scarcely any loss. When the cyana- 

 mide was mixed with kainit, there was no loss even after 

 forty-two days. With superphosphate it was otherwise, and 

 a loss of 5 per cent, was discovered. It would therefore seem 

 neces.sary to avoid making a mixture with this manure. 



The paper in ipiestion contains details of a large number 

 of manurial experiments nu-ried out with various croj)s, such 

 as wheat, oats, maize, jiasture grass, vines, etc. From the 

 results of these trials, the conclusion is drawn that calcium 

 cyanamide is similar in effect to an equivalent amount of 

 sulphate of ammonia. A normal quantity of the manure to 

 apply per acre would be about 200 Bi. This may be given 

 either before, or at the time of sowing. 



