INTRODUCTION 
This Bulletin consists, 1st, of a reprint of an address delivered at 
Kiverside, Cal., on the treatment of Scale-insects, and more particu- 
larly of the Icerya of the Orange, known variously as the "Australian 
Bug," "Cottony Cushion-scale," "White Scale," "Fluted Scale," &c. ; 
2nd, a subsequent communication as to its possible origin and synonymy ; 
3rd, a recent important bulletin from the State University of California 
on the use of gases against Scale-insects. These papers need no further 
introduction and are all supplementary to an extended article upon the 
Icerya, which will appear in my annual report. 
The importance of this insect and of all the different scale-insects af- 
fecting the Orange in California is such as to justify the republication 
of these papers, as there is a constant demand for copies of them. The 
report by Professor Morse on the use of gases is a valuable contribu- 
tion to the advancement of our knowledge and means of protecting 
trees from these scale-insects. It may be looked upon as a direct 
outgrowth of the experiments made for the Department by Mr. D. 
W. Coquillett, as he had just begun to experiment with gases when bis 
commission ended for want of funds. He subsequently continued these 
experiments in a private capacity with more or less success, and that 
which Professor Morse found most satisfactory is, I believe, essentially 
the same as that previously adopted by Messrs. Coquillett, Craw, and 
Wolfskill and referred to in my Eiverside address. What is said in 
that address under the head of "Fumigation" will, nevertheless, 
hold true, no matter how satisfactory the use of these gases may 
become, and Professor Morse's experiments rather confirm the difficul- 
ties which I have indicated in the way of producing a gas which will 
destroy the Icerya and its eggs, as also the danger attending the use of 
any poisonous gas and the greater expense attending the use of gases, 
as compared with washes, especially for those who have few trees 
to treat. Some excellent improvements have been made in the cyclone 
nozzle, whether for facilitating the change of direction or amount of 
spray, or whether for ease of cleansing, and I would especially call at- 
tention to those of John Croften and L. D. Green, of Walnut Grove, 
Cal., and of Vermorel, of France. 
As VermorePs arrangement for cleansing is as yet unknown in this 
country, we may briefly describe it as follows : 
The nozzle is pierced below by a circular orifice of from five to six 
millimeters in diameter, which can be closed by a fly- valve. The reg- 
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