348 



From this tal)le a second fact seems to appear, namely that 

 liopper emergence was reduced in any lialf month when the local 

 rainfall was very heavy. Thns in the second half of October, 191-i, 

 when Alor (iajah had 11.64 inches of rain falling on ten days, there 

 were no hoppers discovered nearer tlian the Negri Semlnlan l)order 

 at a distance of more than eiglit miles; and in the second half of 

 August, 1915, when 10.72 inches fell on 6 days, no hoppers 

 emerged : and again wlien in the second half of October, 1914, 

 Jasin had 12.G1 inches falling on 14 days, no hoppers emerged, or 

 at least none Avere discovered. 



It is quite possible that such an effect could be ])roduced by 

 the evaporation from the Avet ground resulting in a tem])crature 

 just under the surface too low for the eggs to develop. 



Tlie maximum and minimum amounts of rain in balf montbs 

 when hatcliing occurred were : — 



Alor (iajab, maximum 7.63 in amount or 9 in days. 



minimum ".63 in amount or 2 in days. 



Jasin. maximum 6.21 in amount or 13 in days. 



minimum 0.88 in amount or 2 in days. 



The minimum is the absolute minimum of either place during 



tlie ])eriud of the observations. 



Excessive hatching was recorded in iialf montlis whcu ibe 

 rainfall was : — - 



Alor Gajali 3.51 1.86 3.95. 

 Jasin 0.88 4.30 3.58 and 3.84. 



We sum up all tliat we can say then thus: — that we believe 

 the soil moisture in such places as the locusts choose for depositing 

 eggs to l)e in Malacca territory sufficient tbrough nine montbs of 

 the year to allow the eggs to develop, l)ut that excessive rain is 

 lialde to create by evaporation a temjwrature Avhich inhi])its the 

 development. Such a view explains tlie cessation of a]i]3earance 

 of hoppers at the times recorded. 



Mr. F. \y. South has written (Agric. Bull, of the Federated 

 Malay States, iii, 1915, p. 295) " from April to October there is a 

 tendency to a general movement of the locusts in the Malay Penin- 

 sula in a north-westerly direction : while durii^g the remainder of 

 the year the direction is reversed.'" We suspect that the teiulency 

 is different in Malacca and the forces, light winds or whatever they 

 be leading the insects to move southwards, are much stronger than 

 Mr. Soutli's statemput would imply : and further we sus])ect that 

 the tendency sueJJ as it is, sends swarms of fliers down to deposit 

 eggs near the coast, in tlie low land not subject to fires where as 

 enemies are more numerous, the toll taken of the hoppers is greater 

 than in the lallang lands towards the north. This view regards 

 tbe lallang wastes as danger spots, — foci whence the broad coastal 

 riee lands may get infected recurrently, and therefore regards the 

 latter more as a " permissive area " to invading locusts. 



A record has been kept of the nature of the vegetation in 

 which hoppers were observed; and it may l)e siimmed up as fol- 

 lows : — 



