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1 May, 1902.] QUEENSLAND AGRICULTURAL JOURNAL. 337 
here and there upon the surface of the plant. These detrimental modifications, 
however, give rise toa far more significant phenomenon. This arises when 
the maize plant has become grossly infested by the leaf hopper prior to its 
“cobbing.” As previously stated, the insect especially favours the stalk of the 
male inflorescence, or flower-head, and its branches as sites wherein to implant 
its eges. These, indeed, when the gum or extravasated sap has been removed, 
are rough from the presence of the tiny weal-like elevations which illustrate 
this fact. In consequence of this the inflorescence only partially expands, or if 
it does issue and open out, it has been already robbed of its virulence, and can 
no longer liberate pollen wherewith the female flower can be fertilised, as is 
essential for the production of grain-yielding cobs. Indeed, it often happens 
that neither the mechanical injuries nor the physiological changes that these 
give rise to affect the purely vegetative growth of the plant. Hence, in order 
that the disease may ensue and be followed by its full effects, these leaf-hoppers 
must occur in abundance, and must attack the plant at a special period in its 
life-history. Thus it may be that maize that is planted shortly after a long 
period of dry weather—and this is inimical to the increase of the insect—may 
escape some injury itself, although it may serve as the breeding ground of the 
numerous hordes that may destroy such as is later sown. This is probably the 
explanation of the fact that during the present season April planted maize, 
almost without exception, has succumbed to “blight,” whereas that derived 
from seed sown in January, and early in February, has not only not suffered, 
notwithstanding it has harboured—in some numbers—the insects, but has 
yielded good crops. When writing about the “Maize Delphax” in 1889, 
attention was called to the fact that it was not only a native insect but one 
also that has as its host-plant one or more of our indigenous species of grasses. 
This fact must suggest, as a matter of probability, that this insect that is 
injuriously related to grasses somewhat generally, would damage amongst others 
the sugar-cane also, especially so since a species of ‘‘ Delphax” (named D. 
sacchar?) is one of the insect pests of the latter plant in the West Indies and 
elsewhere. Local investigation, however, leads to the conclusion that the 
maize leaf hopper does not resort to the sugar-cane plant except when this is 
growing adjacent to blight-infested maize, and even then does not occasion 
noticeable injury. The sugar-cane in the Lower Burdekin, as well as that 
growing in other parts of the State, does, strange to state, harbour a second 
and distinct species of “Delphax.” This is a true sugar-cane leaf hopper, 
apparently restricted to the plant whereon it occurs. Its habits are similar to 
aoe of its congener. Thus it deposits its eggs in the tissue of the leaf-sheath 
as well as in that of other parts of the plant, giving rise, as a consequence of 
the act, to the red spots and blotches that have of late years been so noticeable 
in connection with this part of the cane-plant in our plantations, and to the 
premature drying up of the older foliage. The sugar-cane ‘‘ Delphax” does 
not, as a rule, occur in such numbers as does the maize ‘“‘ Delphax,” and in so 
much as cane is grown for sugar, and not grain, its presence on the plant that 
it affects is not a matter of such significance as would otherwise be the case. 
With regard to measures to be adopted in coping with the “ Maize 
Blight,” only indications as to the general procedures to be adopted can at 
present be afforded. Preventive treatment, however, is the only one that is 
admissible. In the first place it must be recognised that the blight originates 
in the visitation of an insect from without, or as the outcome of migration of 
recently born insects from one part of the plant to another. We, therefore, 
require to repel the insect, to oust it from temporary possession, or to kill it. 
A noisome spray-wash, pungent smoke and tobacco dust, might be found 
valuable in the accomplishment of these purposes. It should be further borne 
in mind that maize stalks, even when a good crop has been harvested, may 
harbour the eggs of the leaf hopper in very large numbers—much more so the 
stalks of typicaily ‘ blighted” plants. These, therefore, should be gathered up 
and destroyed on the earliest possible opportunity. Preferably, they should be 
destroyed by fire, rather than be ploughed in. At the same time they can, if 
