372 BIOLOGICAL CONTROL 



to do with the adoption of biological control. Encouraged by 

 the early success of Vedalia in California, followed by the 

 subjugation of the cottony-cushion scale in the Islands in 1890 

 by similar means, the growers turned to biological methods of 

 relieving them of the immense damage wrought in the cane fields 

 by the leafho}:)per Perkinsiella saccharicida. The introduction in 

 1905-1906 by Perkins and Koebele of Paranagrus optabilis Perks, 

 from Queensland, and of Ootetrastichus heatus Perks, by Koebele 

 from Fiji, led to a rapid decline in the damage occasioned by the 

 leafhopper. Both these insects are small Chalcids attacking the 

 eggs of their host and, valuable as they proved to be, they scarcely 

 gave the degree of control required by the growers. It became 

 evident that some robuster type of leafhopper enemy was needed 

 which would, at the same time, withstand the bad conditions 

 occasioned by heavy rains. In 1920 Muir introduced the 

 predaceous Capsid bug Cyrtorhinus mundulus (Bred.) from P'iji 

 and Queensland. The habits of this insect are exceptional in that 

 it preys upon the eggs of the leafhopper, whereas other Capsidae 

 are almost exclusively plant-feeders. Muir's observations showed 

 that the habit was a fixed one, and the possibility of its varying its 

 behaviour under new surroundings and becoming a plant pest was 

 happily not fulfilled. After some difficulty the insect became 

 securely established in the Islands, and it is now generally conceded 

 that the Cyrtorhinus has completed the subjugation of the leaf- 

 hopper. The latter, which was once so abundant and so destructive, 

 requires searching for in the cane fields to-day. 



Muir's success with the Cyrtorhinus followed his long journeys 

 in the Orient for the purpose of investigating other sugar cane 

 pests. The cane borer weevil Rhabocnemis obscurq (Boisd.) was 

 one of the pests which demanded a measure of control. Search 

 for the weevil in Southern China, the Malay States, Java and 

 other of the East Indian Islands brought no success, but eventually 

 Muir found the insect in Amboina, and furthermore discovered 

 that it was attacked by the Tachinid Ceromasia sphenophori Vil. 

 Difficulties in transporting living material of the fly to Honolulu 

 proved too great, and it became necessary to discover some other 

 locality from whence it would be easier to effect shipment. After 



