104 
or other injurious insects may be accidentally introduced. In 
this connection, as an instance, it might here be recorded that 
in 1913 Mr. J. C. Bridwell, while in Nigeria, West Africa, 
collected there among other material for study in Honolulu, 
a small Delphacid, allied to our own sugar cane leaf-hopper, 
which Mr. Muir later described as Megamelus flavolineatus. 
During the past year Mr. Muir has received collections of leaf- 
hoppers from Porto Rico (where insects of some sort are car- 
rying mosaic disease in sugar cane) and among these he found 
this West African species of which Mr. Wolcott, the entomolo- 
gist in Porto Rico, remarks: “The identification of J7. flavo- 
lineatus was especially fortunate, as this is a cane insect which 
may become a serious pest.” The fact, therefore, that these 
insects convey many plant diseases also makes their study 
necessary for economic work. Knowledge acquired purely 
from scientific studies sooner or later is the foundation of 
applied practices, as is well instanced in the “Fauna Hawaii- 
ensis,’ without which we never could have handled our local 
entomological problems with the same degree of certainty. 
The present tables summarize our knowledge of the dis- 
tribution of the endemic Delphacidae in our islands and further 
adds to the lists of their food plants as previously published.* 
As is to be expected, the species having all or many long- 
winged forms have a wider distribution than those having only 
a few or no long-winged forms. The comparative paucity of 
Alohini on Kauai and comparative richness of Leialohini is of 
interest and may indicate that that island was separated from 
the others before the arrival of Delphacidae in the Archi- 
pelago. The distribution shows the value of segregation in 
species formation, which fact is also shown by the lists of 
food plants. ‘Those species living on two or more plants show 
much greater variability than those confined to a single plant. 
When we consider the topography of the islands, the isolated 
distribution of many plants and the fact that so many species 
are represented only by short-winged forms or by only an 
occasional long-winged form, we can see how isolation can 
take place even on the same island. 

* Proc. Haw. Ent. Soc. III, No. 4, May, 1917, p. 339 et seq. 
