28 THE SUGAR-CANE INSECTS OF HAWAII. 
It may be that it would be better, at least from the disease point of view, if the 
harvesting of the fields were more in the nature of a clean sweep. If the diseased 
sticks are not too numerous they would not seriously interfere with the working of 
the mill. The advantage would be that whatever diseased material was thus dealt 
with would be dealt with in the very best manner, that is, it would be utterly de- 
stroyed. 
NATURAL ENEMIES. 
SpeEcIES ALREADY PRESENT IN THE ISLANDS. 
Many beneficial species of insects, already present in the islands 
at the time of the leafhopper invasion, adapted themselves to the 
leafhopper as a source of food. The following species were noted 
during 1903: 
A ladybird beetle, Coccinella repanda Thunb., one of Mr. Koebele’s 
Australian introductions, was particularly abundant in the cane 
fields and the larva did good work against the young leafhoppers. 
An enemy of this species, the hymenopterous parasite Centistes 
americana Riley, has found its way to the islands and will no doubt 
reduce the effectiveness of the ladybird. The writer observed also 
the ladybird Platyomus liwidigaster “Muls. in the cane fields. A 
predaceous bug, Gchalia griseus Burm., was found in large numbers 
in the infested cane fields on the Island of Hawaii. The larve of 
two lacewing flies, Chrysopa microphya Mclachl., and Anomalochrysa 
sp., were observed feeding on the young leafhoppers, the first species 
being particularly abundant in some localities. 
Several species of spiders were abundant in the cane fields and 
were active enemies of the leafhopper. The writer collected two 
species, Tetragnatha mandibulata Walck. and Adrastidia nebulosa 
Simon. On the writer’s advice large numbers of the ege-nests of 
spiders were collected in the localities where they were abundant 
and placed in sections where they had not as yet become established 
in the cane fields. 
In the forest above the Kohala district, on the island of Hawaii, 
the writer found a fungous disease infecting to a great extent the 
common leafhopper Siphanta acuta Walk., a species belonging to the 
same family as the cane leafhopper. Quantities of this fungus 
were distributed in the cane fields in the hope that it would infest 
the cane leafhopper. No striking results were obtained, though 
diseased cane leafhoppers were found in some of the rainy districts. 
Several species of ants were very active about the leafhoppers in 
the cane fields, the honeydew being an attraction to them. 
Doctor Perkins mentions further in his early report a predaceous 
bug, Zelus peregrinus Kirk., and describes as new a hymenopterous 
parasite of the leafhopper under the name Ecthrodelphax fair- 
childii Perk.? 
@ Perkins, R. C. L.~—Bd. Comrs. Agr. and Forestry, Hawaii, Div. Ent., Bul. 1, 
pp. 20-22. 
