In respect of insect and, incidentally, fungous diseases of plants, Mauritius is remarkable in two respects; the first being the very small numberthat 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 established 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 greatdamage was done by the insect known locally as the “Pou a Roche Blanche” (Pulvinaria gasteralpha, Icery); 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.