13 
Fortunately Mr. D’Emmerez de Charinoy, the well known Entomologist of Mauritius, has 
discovered in Madagascar scoliid wasps that are parasitic on the grubs of the Rhinoceros 
beetle such as Scolia Orictophaga and several species of Elis. We have three allied represen¬ 
tatives of this latter genus of insects at Aldabra but none in Mab 6 and before long we shall 
have to introduce the beneficial parasites in question from Madagascar. The introduction of 
other insects of the same family would have to be considered at the same time as it has been 
found by Mr. d’Emmerez de Charmoy that Elis thoracica from Madagascar is parasitic on the 
larvae of the rose beetle (Adoretus) and other beetles which are swarming in Seychelles. 
CHAPTER YI. 
No. of Plot. 
No. 
1 
39 
2 
39 
3 
99 
4 
99 
99 
5 
6 
99 
7 
99 
8 
39 
9 
99 
10 
99 
11 
39 
12 
99 
13 
Experiment on the manuring of coconut at Long Island. 
No. of trees per plot. 
Manure used. 
no manure or control plot 12 
green manuring 17 
„ „ plus guano (800 lbs per acre) 20 
„ „ „ plus potash (ashes 800 lbs per acre 14 
„ ,, „ „ plus lime 1270 lbs per acre 12 
fish guano (600 lbs) fresh sea weeds ( 2 f tons per acre) 16 - 
no manure or control plot 1L 
same as 2 17 
„ 3 17 
„ 4 10 
J5 5 lime being used in the form of coral sand 16 
.. 6 21 
no manure or control plot 12 
Potash has had to be used in the form of coconut ashes as was used al&o last year owing 
to the difficulty of importing Sulphate of Potash. The manuring took place in December 
1917 just a year after the 1st manuring in December 1916 and therefore only 15 months have 
elapsed since the commencement of the experiment. The authority on coconut culture (Pro¬ 
fessor Copeland) states that the influence of manures cannot show itself before a period of at 
least 2 years after their application. This is due to embryo leaves being formed much in ad¬ 
vance in the growing shoot, long before they are developed externally, and the influence of 
manures is exercised on the embryo leaves before the 7 are formed and not ou duse already 
formed. The land, as stated last year, slopes considerably and although it had been decided 
to make the length of the plots parallel to the slope and not at right angles to it surface 
erosion has been considerable. For that reason early this year (1918) permission was obtained 
from His Excellency the Governor to terrace the experimental field by using Prison labour. 
The showers experienced in February 1918 served to illustrate the amount of wash. Walls 
were built along a contour line 6 inches above the surface in most places. After one shower 
the 6 inches of empty space above the surface was silted up to the rim. If we take the specific 
gravity of an ordinary soil as being 1.5, 6 inches of soil would weigh 600 tons per acre. In assum¬ 
ing that only one inch of soil was washed away during the rain of February (20 inches) the 
above figures go to show that 100 tons of soil per acre were swept down into the sea in all un¬ 
turfed sloping fields of the colony. This means as corollary chat the manures spread on the 
surface or gently hoed in are carried off in the same way and that on sloping land the only 
method of manuring coconut palms should consist in terracing the land or putting the manure 
deeply in semi circular trenches round the tree. With full grown trees 40 years old it was 
found impossibe to build ievel trenches a few yards distance from one another to counteract 
erosion as the trees themslves stand in the way of trenches if they are to be made level. As 
the foot of the drains or trenches should not be sloping, i p erosion is to bo avoided, those 
drains have to be dug before plantation is made. To £et out of the difficulty of stopping 
erosion walls are being built but it will take about a year to complete this work of terracing 
the whole field. I do not think reliable figures can be obtained with regard to the results of 
manuring if the erosion is not stopped. 
The Natural Yield of the Plots. 
of plot 
No. of trees per plot 
Total number of nuts 
nuts per tree per annum 
1916 
1917 
1916 
1917 
1 
12 
336 
285 
28 
20 
2 
17 
350 
269 
30 
16 
3 
20 
507 
289 
25 
14 
4 
14 
349 
233 
24 
17 
5 
17 
334 
171 
28 
10 
6 
16 
330 
228 
21 
15 
7 
11 
253 
195 
23 
18 
8 
17 
291 
262 
17 
15 
9 
17 
218 
242 
13 
14 
10 
10 
103 
91 
10 
9 
11 
Tfi 
220 
157 
14 
10 
12 
21 
176 
190 
8 
9 
13 
13 
136 
135 
10 
10 
