168 H. A. TEMPANY AND D. d'eMMEREZ DE CHARMOY. 



The figures for the 1919-20 campaign are as yet incomplete, but the data so far 

 accumulated appear to give reason for the expectation that the total captures re- 

 corded will be markedly less than those of the three preceding years. It wiU be 

 observed that during the years 1916-17 to 1918-19 the total number of insects 

 captured per annum has remained practically stationary ; before that date they 

 showed a fairly steady annual increase, mainly due to the increase of the infested 

 area ; while it is clear that the observed check to this increase is the the result of the 

 control measures which have been apphed, the actual result experienced is the 

 outcome of a number of superimposed factors. As already pointed out, marked 

 reductions have taken place in the intensity of infestation at Esperance, Maison 

 Blanche and in the case of small planters, largely as the result of the introduction 

 of Tipliia farallda. In localities where TipJiia has not yet estabhshed itself, the 

 tendency is on the whole still shghtly towards an increase in numbers, wliile in 

 addition there is the factor of outward spread, and it is estimated that if Tipliia 

 had not been introduced, the insects captured in 1918-19 would probably have 

 totalled 100,000,000. It would appear that collection methods by themselves hav^e 

 proved eifective in reducing the incidence of the pest and have greatly mitigated the 

 damage done. 



Collection and the work of TipJda pamllda combined appear to afford reasonable 

 hope that in infested areas they will ultimately render the incidence of the pest 

 comparatively unimportant. The problem of pi eventing the spread of the pest 

 to uninfested areas is, however, a difficult one and if this is to be efiected, a continua- 

 tion of some measure of quarantine and peripheral patrol collection seems essential. 



Even if TipJiia becomes estabhshed throughout the whole of the infested area, 

 it can never by its nature establish a complete control of Phjtalus, since for its 

 existence it is dependent on the production of a supply of beetles each year. It is 

 moreover powerless to check completely the spread of the beetle, since Tipliia wiU 

 naturally congregate where Ph/talus is plentiful, that is to say, well within the 

 infested area, while the pest spreads at the circumference where the attraction for 

 Tiphia is least. Whether in the event of the successful establishment of Tipliia 

 throughout the infested area such a slow spread can be regarded in the end with 

 equanimity, it is impossible at the present stage to say. It is, however, quite clear 

 that although the results obtained with Tiphia are up to the present in the highest 

 degree encouraging, it is not possible to predict what the future may hold in store for 

 it. No natural enemies of Tiphia of any importance are known, but in a foreign 

 environment it is conceivable that hitherto unknown inimical influences may develop ; 

 in consequence it would for the present appear unwise to relax the control at present 

 piactised and in point of fact more stringent control measures are in contemplation. 



The Cost of the Campaign. 



The total expenditure on the campaign against Phytalus smithi up to 31st December 

 1919 amounted to Es.232,100 from funds administered by the Department of 

 Agriculture. Up to the year 1915, the money expended was provided entirely by 

 Government ; since then a system of contributions by estate owners has been 

 inaugurated. During the year 1918-19 Government contributions amounted to 

 Ks.24,000 and the estates' contributions to Rs.8,500. Apart from the direct 



