108 
Mueller, in '-Kuealyp1o<rniphia,'' says : "The real and special interest of Ema- 
lyptusviminalisis concentrated in the fact that it is this particular species which mainly, 
if not almost solely, furnishes the melitose-manna." I have already shown that this 
is not correct. 
Other references to E. mminalifs will be found at p. 111. 
3. -Zoological Notes on Eucalyptus Manna. 
It will surprise a good many people to be informed that very little is known 
from the entomological side as to the biology of manna. 
The following extracts from letters by Mr. Froggatt to me arc in point': 
My experience is that under certain conditions the injury to foliage by many insects, cockchafer 
beetles, and many homoptera will cause an encrustation of crisp white manna, but the Cicadas do not cause 
the large quantities of manna that fall from the Peppermint Gums (E. cinerea var. nova-anglica) in the 
New England district. The season (1915) I was at Uralla, in the early summer, the manna was thick under 
the clumps of trees long before the first Cicada appeared, and I could find no insects puncturing the foliage. 
I could have filled a half pint tin in a few minutes with the crisp, crinkly manna that you find under the 
trees in large quantities. The same remarks as to absence of Cicadas apply to a place below Goulburn. 
From here I had a large quantity of similar manna sent, that had been collected in a similar manner on the 
ground not in country frequented, even in summer, by many Cicadas. (? E. mbida.) 
Our manna is not produced by Cicadas; a little is often caused by frog-hoppers of the Genus 
Eurymela, but this is only local. What is the origin of the large quantities I do not know. 
At the back of Manly some years ago the Red Eye or Black Cicada (C. mocrens) used to swarm over 
the stems of the smooth-stemmed White Gums in the gullies, and when disturbed used to discharge a regular 
spray of liquid ; this species is much more prolific in this way than any other species, yet this liquid never 
formed manna on the ground under the trees, it simply remained as a honey-dew glazing the foliage. As 
far as my observations have gone, I have never been able to convict any Cicada of producing manna of any 
kind, yet at Terrigal I have counted 400 on the trunk of a large gum in the early morning. 
I trust that a research will be undertaken in regard to the entomology of manna. 
The exudation of this substance has been attributed to the Order Hemiptera, Sub- 
Order Homoptera, in its Families Cicadidae, Cercopidae, and Psyllidse; and also to 
Coleopterjv A few notes are submitted, and it will be observed that some are the 
Work of non-entomologists, while others have been repeated by authors without separate 
inquiry. It is for the entomologists to separate the various kinds of manna (including 
the Lerp). and also to correlate the different kinds of insects to their corresponding 
mannas. 
According to tin- suggestion of Darwin, in the following passage (and note the 
reference in the M;MIM;!, Ash), the question of the flow of manna may be a physiological 
one, and the insects, cither as hv.l'-mtins. i,r EM wood or ln'.ik-bnrers, may be mere 
moeli;:iM-,- 1 ;:irri'ts '] releasing the now of s.-.eehii.rine sap. 
M"' 1 JO I suggested that primarily the saccharine matter in HIM tin \\as excreted as a waste 
product df chemical chair.."' in tin jap; and that when the excretion happened to occur within the envelope 
of a flower, it was ut ilised fur the impnrtiiui ( ,l.ject of cross fertilisation, bein;; subsequently much increased 
in quantity and stored in various ways. This vi< \v is rendered probable bv t he leaves of some trees excreting, 
under certain climatic conditions, without the aid of special glands, a saccharine fluid often called honey-dew. 
