CONTROL OF PRICKLY PEAR 417 



very prevalent in recent years in the Northern Province, and it is 

 believed to be an accidental introduction from Madras. Dactylopius 

 ceylonicus does not appear to be capable of exercising any con- 

 trolling influence over this plant, a fact which led to the 

 introduction in 1924 of D. tomentosus (opuntice) from Australia. 

 According to Jepson, the experiment has proved remarkably 

 successful. A large area of scrub in the neighbourhood of 

 Trincomalee was cleared by its agency in eighteen months. It 

 has also given equally satisfactory results in other districts, land 

 which was previously occupied by Opuntia scrub, 6 to 10 feet high, 

 is now under cultivation. 



In 1926-27 consignments of Dactylopius tomentosus were 

 forwarded to Mysore and to Tuticorin with the object of 

 endeavouring to control Opuntia dillenii. The insects have 

 become established and it is stated that an area of 40,000 square 

 miles is now covered by the cochineal in southern Madras. Very 

 large tracts of land have been cleared through its agency, and land 

 so liberated has now come under cultivation for the first time for 

 many years. It is further claimed that the whole prickly pear area 

 of 114,000 square miles offers prospects of being cleared by 1940, 

 judging by the progress so far achieved. As Jepson remarks, if 

 this forecast be fulfilled, the experiment promises to become a 

 classic example of the control of weeds by biological methods. 



Several species of Opuntia have become troublesome pests in 

 Mauritius, notably 0. tuna and 0. monocantha. The introduction 

 of Dactylopius ceylonicus by d'Emmerez de Charmoy resulted in 

 rapid destruction of Opuntia monocantha, and in his 1929 report 

 on the subject it is stated that within fifteen years this plant has 

 become completely controlled on the Island. The introduction of 

 D. tomentosus from Ceylon in an attempt to control 0. tuna is a 

 much more recent experiment. Its establishment has proved 

 successful and this prickly pear has been cleared from large areas. 



In Madagascar it appears that rather an anomalous state of 

 affairs exists. R. Decary states that Opuntia dillenii was formerly 

 prevalent in a wild state on uncultivated land and was a local 

 fodder plant. Since 1924 the commercial cochineal Dactylopius 

 coccus entered Madagascar under accidental circumstances, it is 



K.A. EXTOMOLOQY. - 14 



