171 



NOTES ON INSECTS ACCIDENTALLY INTRODUCED INTO THE ISLAND 



OF MAURITIUS. 



By D d'EMMEREZ de Charmoy, 

 Government Entoinologist. 



In respect of insect and, incidentally, fungous diseases of plants, Mauritius is 

 remarkable in two respects ; the first being the very small number that are indigenous 

 to the island, and the second the very large numbers that have been introduced. The 

 desire to introduce exotic plants of a useful or ornamental nature is very widely 

 spread in this Colony, and very extended plant introductions have taken place. 

 Until comparatively recently no restrictions existed on such importations, and as 

 a result insect and fungous pests in large numbers have become estabhshed to the 

 great and permanent detriment of the major and minor agricultural industries of 

 the Colony. For example, the cane-sugar industry was threatened with ruin in 

 1842 as the result of the introduction of the borer, Proceras saccchariphaga, Bojer, 

 from Ceylon ; at a somewhat later date great damage was done by the insect known 

 locally as the " Pou a Roche Blanche " {Pulvinaria gasteralpha, leery) ; and again 

 quite recently the introduction of Phytalus smithi has proved a serious menace to 

 the industry and has resulted in the loss of large sums of money. 



Minor industries have suffered in a corresponding degree. For example, the 

 cultivation of coffee and vanilla has been in large part abandoned, partly as the 

 result of the incidence of introduced cryptogamic diseases ; while in general it has 

 been shown in another paper that out of 80 species of insects recorded as pests of 

 minor crops in the Colony, 50 (or 62*5 per cent.) are of exotic origin. 



In relation to official measures of control, the first action taken was in the year 

 1882, when an ordinance was passed dealing with the introduction of pests of the 

 grape vine, the legislation being the outcome of a convention entered into by the 

 local authorities with the Government of the Cape of Grood Hope. 



Until 1910, no other protection was afforded ; in this year a second ordinance was 

 passed empowering the Collector of Customs to destroy, or cause to be treated, plants 

 and other articles, the importation of which was liable to lead to the introduction 

 of pests and plant diseases. The ordinance remained inoperative until 1911, when, 

 by proclamation, the powers thereunder were transferred to the Director of Forests. 



In 1913, the regulations under these ordinances were again revised, under Pro- 

 clamation 81 of 1913, whereby the restrictions were made more comprehensive, 

 and executive powers transferred to the Director of the then newly organised Depart- 

 ment of Agriculture. 



Since that date a regular and efficient control has been exerted over plant importa- 

 tions. The text of the Ordinance and the regulations made thereunder are given as 

 an appendix to this paper. 



It is impossible, at the present time, to trace the manner in which many of the 

 older insect pests of crops were introduced into the island, or even to give the exact 

 date of their introduction. 



