32 THE SUGAR-CANE INSECTS OF HAWAII. 
one who has paid the least attention to such matters can doubt that it would some time 
since have become impossible to raise any crop of sugar cane in the islands. The reason 
why these natural enemies have not alone got the upper hand of the hopper is due 
to various causes. In the first place, a number of the parasites such as the Dryinid 
Ecthrodelphax fairchildii and the parasitic flies of the genus Pipunculus are of local 
occurrence, and in many places cannot (for climatic or other unknown reasons) 
maintain their existence. This was well shown by the behavior of the first-named, 
which was distributed in thousands by the entomologists and the Plantation man- 
agers themselves to all the districts in the islands, but in many places did not thrive. 
Such, too, is the case with the predaceous black earwig (Chelisoches morio) which, a 
natural immigrant to the islands and no doubt acclimatised centuries ago, is found 
on comparatively few plantations. Other natural enemies are themselves periodically 
decimated by parasites, as is the case with the introduced green cricket (Xiphidium 
varipenne), which has its own egg-parasite (Paraphelinus). Other enemies like the 
common lady-bird (Coccinella repanda) introduced by Koebele years ago for other 
purposes, prey on young leaf-hoppers, in default of more favorite food, and this valu- 
able predator too is itself subject to parasitic attack by the common Braconid (Cen- 
tistes). At present the whole number of parasites and predaceous insects that attack 
cane leaf-hopper to such an extent as to render their services worth noting is consid- 
erable, as the following summary shows. 
The most valuable are the four egg-parasites, which there is every reason to hope 
will become still more effective with reasonable time, one (Ootetrastichus) having as 
yet had no chance to show its full effectiveness. 
The two Pipunculus flies (Pipunculus juvator and terryi) are restricted to certain 
localities and are native species, which have transferred their attacks from native 
Delphacids to the cane leaf-hopper. 
The ubiquitous lady-bird (Coccinella repanda) is valuable as a destroyer of leaf- 
hopper, though originally imported by Koebele to destroy Aphis. It is hoped that 
other lady-birds, especially Verania strigula, may become established and do good 
work, as in Australia and Fiji, whence they were imported. 
The earwig Chelisoches morio is a local species, but no doubt useful where it exists 
in numbers. : 
The green cricket (Xiphidiwm varipenne) is very valuable, but is most unfortunately 
heavily attacked at certain seasons by an egg-parasite. 
The Dryinid Ecthrodelphax fairchildii is locally valuable. At certain seasons in 
suitable, but limited, localities, it destroys a considerable percentage of hoppers. 
Its services are underestimated because for a large part of the year it lies as a dormant 
larva in the cocoon, and parasitized hoppers at such a time are naturally hardly to be 
found. 
There are many other natural enemies of more or less importance, e. g. the various 
predaceous Hemiptera, and the several lace-wing flies (Chrysopine). 
In addition to these insect enemies, we must mention the two fungous diseases of 
hoppers (amounting locally and at certain seasons to epidemics) which, long previ- 
ously known to kill the native leaf-hoppers, have become transferred to the introduced 
pest. We also found one or more fungous diseases attacking leaf-hopper eggs in Fiji 
and Australia in all localities. With material imported from these countries, I easily 
infected eggs of the cane leaf-hopper under cover, and subsequently established the 
fungus at large in the field. As it was most probable that parasitized and healthy 
hopper eggs would be affected alike by the disease, and consequently many of the egg- 
parasites would be destroyed, it became a subject of discussion whether we should 
attempt to establish the fungus or not. As, however, throughout Australia, the 
fungus and parasite both attacked the eggs, Mr. Koebele was of opinion that we 
should try and establish the same conditions here. Consequently with the first 
