174 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9^ 



It was first found harmful to sugar in 1902. It spread rapidly, and 

 in 1903 damaged the crop to the extent of three millions of dollars. 

 That year Koebele came to the United States to look for parasites. 



In 1904 Koebele and Perkins went to Australia; got more than 

 one hundred species of parasites of leaf-hoppers, and although failing, 

 with their first consignment sent in cold storage from Cairns, later 

 shipments from Bundaberg were successful. They were reared in 

 confinement and liberated in cane fietds. 



The year 1904 showed enormous loss from the leaf-hopper on many 

 plantations. In 1906 certain of the parasites began to multiply very 

 rapidly. 



In 1907 one very large plantation, owned by the Hawaiian Agricul- 

 tural Company, whose crop had dropped from 10,954 tons in 1904 

 to 1,620 tons in 1905 and to 826 tons in 1906, made the next year 

 11,630 tons almost entirely as the result of the parasite introduction. 



Silvestri visited the islands in 1908 and reported with enthusiasm 

 on the results of the introductions. 



During August, last, the situation with regard to the sugar cane 

 leaf-hopper on the island of Oahu was almost perfect. The canes 

 were not damaged in any respect so far as I could see. The leaf- 

 hoppers were still present, but in insignificant numbers; where they 

 had oviposited their eggs were almost invariably parasitized either by 

 Paranagrus or Ootetrastichus. 



I was told that there is an occasional reviving of the.leaf-hoppera 

 in numbers, following the destruction of parasites by trash-burning, 

 and that, at that time, on one large plantation on the island of Hawaii, 

 1,000 acres was so badly infested that a yield of only one-half a normal 

 crop was expected; but these recrudescences are and probably will be 

 fugitive. 



No other leaf-hopper parasites were seen. Some of the parasites 

 of the adults, notably Haplogonatopus (a Dryinid), I was informed, 

 still exist on the islands. 



The Sugar Cane Borer and its Parasites 

 The sugar cane weevil borer, Rhabdocnemds {S'phenophorus) obscurus,. 



has been a pest on the islands for very many years. 



After the success of the egg parasites of the leaf-hopper in 1904-5, 



the Planters' Association began to search for parasites of the weevil. 



F. Muir started on an exploring trip, and in 1908 found a Tachinid fly 



(Ceromasia sphenophori Villeneuve) at Amboina in tlie East Indies 



parasitizing a weevil infesting sago palms, sometimes destroying. 



90 per cent of the borers, the weevil being probably only a geographic 



variety of the sugar cane species. 



