148 CHAPTER IX 



moth borer. A species of Botrytis is known to cause the death of the cater- 

 pillars of Psalis securus in Java, and a scale louse, Aleyrodes longicornis, 

 attacking fruit trees in Florida and also known as a cane pest, is attacked 

 by a fungus, Aschersonia aleyrodis.^^ Ritchie also records the very effective 

 control exerted by Fusarium sp. on the cane fly in Jamaica.^' 



The recognition of the natural balance suggested the means whereby 

 insect epidemics can be placed under control by the introduction and en- 

 couragement of the parasite or natural enemies of the pest. The credit 

 for the recognition of this means, and also for its successful operation 

 is due in the first place to Koebele,^^ who used it with pronounced 

 success in controlling scale insects on fruit trees in California. In this instance 

 the chief pests were various coccids, one of the most dangerous being the 

 white scale, Icerya purchasi. This was brought under control by the intro- 

 duction from Australia of a lady-bird predator, Vedalia cardinalis. Koebele 

 afterwards became connected with the Hawaiian Sugar Planters' Association 

 and associated with Perkins, Craw, Swezey, Kirkaldy and Muir, who were 

 also employed by the Association. About 1900 a serious epidemic of leaf 

 hopper broke out in Hawaii. It was recognised that the introduction was 

 from Australia, and expeditions were soon despatched there. The parasites 

 of the leaf hopper were found, collected, and imported to Hawaii under careful 

 control. The result was that in a short period the leaf hopper was very 

 materially diminished in number. Of the numerous parasites imported, 

 the most effective were egg parasites, amongst these being three myramids, 

 Paranagrus optabilis, P. perforator and Anagrus frequens. A chalcid, Ooie- 

 trastichus heatus, and a dryinid, Ecthrodelphax fairchildii, belonging to the 

 local fauna, were also useful.^^ 



The success which attended the natural control of the leaf hopper stimu- 

 lated the Hawaiian Sugar Planters' Association to attempt a similar control 

 over the borer beetle, Rhabdocnemis {Sphenophorus) obscurus. This insect 

 had been introduced into Hawaii, probably in 1854 along with the consign- 

 ment of cane that had formed the parent stock of the Lahaina cane. By 

 that time (1905) it had come to be looked upon as a necessary evil. Certain 

 districts were more severely affected than others, the amount of damage 

 done varying with season. The problem was to locate the original habitat 

 of the borer, to ascertain its natural enemies, and to transport them to Hawaii 

 unaccompanied by any hyperparasites which might be present. This task 

 was assigned to Muir, who, starting his search in Southern China, finally 

 located the borer beetle in Amboina (Lat. 8° S., Long. 125° E.) in 1908, and 

 afterwards in New Guinea, where he established himself. As anticipated, 

 the borer was found to be efficiently controlled, the parasite being a tachinid 

 fly, Ceromasia sphenophori. The introduction of this parasite presented 

 unexpected difficulties, and it was only after the establishment of intermediate 

 breeding stations at Brisbane and Fiji that it reached Hawaii ; once there 

 it became rapidly established, and succeeded in effectively controlling its 

 host, reducing the annual destruction of cane to a small figure. ^^ j^g ^.^q 

 instances quoted above are those to which most attention has been attracted ; 

 some others may, however, be noticed. In 1910 an epidemic due to a beetle 

 root-borer, Phytalus smithi, appeared in Mauritius. ^^ It was ascertained 

 that the insect had existed almost unnoticed in the British West Indies, 

 where it was effectively controlled by a scolid wasp, Tiphia parallela, which 

 was then introduced into Mauritius. In this instance the importation had 

 undoubtedly occurred along with some canes coming from Barbados. 



