30 THE SUGAR-CANE INSECTS OF HAWAII. 
short stay of about ten days gave ample proof of the existence in Australia of a con- 
siderable variety of Hymenopterous parasites of leaf-hoppers, of Dipterous parasites 
of the genus Pipunculus, and of Stylopid parasites of the genus Elenchus. 
At Bundaberg, about twelve hours by rail north of Brisbane, we spent another 
ten days in June. Here is an extensive cane district with our leaf-hopper every- 
where present, but never in numbers such as we are accustomed to in these islands. 
In fact we never saw the hoppers nearly as numerous as they are on our least affected 
plantations. From eggs collected here Mr. Koebele soon bred out specimens of the 
Mymarid parasites he had felt so confident of finding. 
From our observations on the habits of the cane leaf-hopper in these islands, it 
seemed probable that in tropical Australia this species would be in its greatest numi- 
bers in the colder months, so after a brief stay in Bundaberg, we proceeded north to 
Cairns, Which place we reached at the beginning of July. This plan seemed very 
expedient, for by retreating gradually towards the south, as the hot season advanced, 
we hoped to prolong the season during which natural enemies for the cane leaf-hopper 
could be obtained. It appeared likely that effective work could cnly be done at 
Cairns for a month or two, since without a reasonably large supply of hoppers, it was 
evident that the parasites could not be found in sufficient numbers for shipment. 
This indeed proved to be the case, and by the end of August, leaf-hoppers and their 
eges had become so scarce in the cane fields, that we came south again to Bundaberg. 
At Rundaberg we made a long stay on this occasion, regularly sending o‘f consign- 
ments of parasites, until here too, owing partly to the season and partly to the harvest- 
ing of the crop, the locality became unprofitable. After a short stay in Brisbane, 
at the end of the year, I returned to Honolulu, while Mr. Koebele proceeded to Sydney, 
where his attention was largely given to collecting beneficial insects for pests other 
than leaf-hopper. On the return journey Mr. Koebele spent one month in Fiji, the 
enemies of the cane-hopper in those islands being mostly similar to those already 
found in Australia. <A fine consignment of the Chalcid egg-parasite (Ootetrastichus) 
of Jeaf-hopper was most important, as it enabled us to establish that important species 
without any doubt. 
During January and February, 1906, Mr. F. Muir continued the 
work in the Fiji Islands begun by Mr. Koebele in the latter part of 
1904. He reported as follows concerning the Fijian sugar-cane leaf- 
hopper and its parasites :? 
The Fijian sugar-cane leaf-hopper (Perkinsiella vitiensis) | found all over the island, 
but it does no damage, being kept in check by several natural enemies. 
The most important of these are the egg-parasites, Ootetrastichus, Anagrus and 
Paranagrus. ‘The first of these was introduced from Fiji into Hawaii by Mr. Koebele, 
and the other two appear to me the same as the Queensland species. In some fields 
as many as 90 % of the hopper eggs were parasitized, but in other fields it was lower. 
Observations extending over my six months’ stay, and made at the various parts of 
the island visited, show that an average of 85 % of hopper eggs were destroyed by 
these parasites. These figures are cnly approximate, as I have to estimate that one 
Chaicid (Ootetrastichus) destroys four hopper eggs, which is a low estimate. This 
Chalcid is more numerous, and on account of destroying the whole batch of hopper 
eggs, is of very much higher economic value than the Mymarids. 


a Muir, I’.—Notes on some Fijian insects. <(Hawaiian Sugar Planters’ Exp. Sta., 
Div. Ent., Bul. 2, p. 3, November, 1906. 
