34 THE SUGAR-CANE INSECTS OF HAWAII. 
daily be distributing thousands of natural enemies, that should control these. Al- 
though such a plan or modification of it might be adopted on some plantations, on 
others (at least such as are under irrigation) it would either be difficult, or altogether 
impracticable. Only in the case ofsome fields of long ratoons would the matter be very 
simple, when a small area of the original ratoon growth in each field could be left uncut, 
and if well supplied with hoppers and their natural enemies would serve later on to 
stock the rest of the field. Unfortunately, owing to the fact that ratoons are (except in 
unusual cases) not severely attacked as compared with plant-cane, this matter becomes 
one of minor importance. Otherwise, in the majority of cases, owing to the clearing of 
large areas and the burning of trash, it is probable that new fields will have to be sup- 
plied by cages similar to those already used. ‘Two things will be absolutely necessary: 
(1) that the new fields be well supphed with parasites; (2) that they be stocked imme- 
diately the hoppers enter them and commence laying. This plan, though less satisfac- 
tory than would be the other method, is nevertheless simple, and does not call for 
much expenditure of time, nor for skilled labor. The one thing necessary to be posi- 
tively ascertained is that the spot whence the cuttings for distribution are taken is well - 
supplied with al/ the kinds of parasites that it is desired to establish in new fields. It 
is now well known to us that all these destroyers are not yet established in all parts of 
all plantations, and therefore at present unless an entomologist previously test samples 
from the spot, whence distribution is to be made, it is quite likely that some of the 
most valuable parasites will not be taken to the new fields. Iiasample be submitted 
to the entomologists, it can be passed as fit to supply all necessary parasites to new 
fields, or if not, cages of the deficient species can always be supplied from the cane in 
the grounds of the Experiment Station in Honolulu. As the parasites are continually 
spreading and increasing, such expert examination will at the most be necessary for a 
year or two; for it is perfectly certain that by that time all the species will be so gen- 
eral that it will be quite impossible to take any extensive sample of cane-leaves that 
bear eggs of leaf-hopper, which will not contain all: Such in fact is now the case in the 
cane at the Experiment Station. To sum up, the clearing of all cane from large acre- 
ages is a decided obstacle to the complete success of natural enemies of leai-hopper, and 
the burning of trash ageravates the difficulty. As an offset to these conditions new 
fields shou!d be supplied artificially with natural enemies, and they should be supplied 
as soon as any leaf-hoppers enter them. Of course future observation may prove this 
distribution unnecessary, but for the present it should be adopted. 
RELATED SPECIES. 
The Hawaiian sugar-cane leafhopper does not occur on the mainland 
of the United States. The insect is closely related to the corn leaf- 
hopper (Dicranotropis maidis Ashm.), common on corn in the South- 
ern States. A West Indian species of leafhopper is recorded as inju- 
rious to sugar-cane, by Westwood, in 1841, under the name Delphaz 
saccharwora and is a member of the same family of insects as the 
Hawaiian sugar-cane and the corn leafhoppers.? Three further spe- 
cies of this same family, the Fulgoride, are recorded as sugar-cane 
pests in Java by W. van Deventer.° 
@ QuainTANCE, A. L.—Fla. Agr. Exp. Sta., Bul. 45, 1898. 
6 Westwoop, J. O.—Mag. Nat. Hist., vol. 6, p. 407, 1841. 
¢ Phenice maculosa, Dicranotropis vastatriz, and Eumetopina kriigeri. Van Deventer, 
Handboek ten dienste van de Suikerriet-cultuur en de Rietsuiker-Fabricage op Java, 
II. De Dierlijke vijanden van het Suikerriet en hunne Parasieten. Amsterdam, 
pp. 167-169, 1906. 
