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U. S. DEPARTMENT OF AGRICULTURE.

division oe entomology.

Bulletin No. 15.

THE

IGERYA OR FLUTED SCALE,

OTHERWISK KNOWN AS THE

COTTONY CUSHION-SCALE.

[REPRINT OF SOME RECENT ARTICLES BY THE ENTOMOLOGIST AND

OF A REPORT FROM THE AGRICULTURAL EXPERIMENT

STATION, UNIVERSITY OF CALIFORNIA.]

WASHINGTON:

GOVERNMENT PRINTING OFFICE,

1887.
404— Bull. 15

CONTENTS

Page.

Letter of Submittal 5

Introduction 7

The Scale-insects of the Orange in California, and particularly the Icerya or

Fluted Scale, &c 9

Notes on Icerya — Its probable Origin the Islands of Bourbon and Mauritius. .. 27

The Use of Gases against Scale-insects . 35

3

V

LETTER OF SUBMITTAL

Department of Agriculture,

Division of Entomology.

Washington, D. C, June 27, 1887.
Sir: I have the honor to submit for publication Bulletin No. 15, from
this Division, prepared under your instructions.

Eespectfully, O. Y. KILEY,

Entomologist.
Hon. Norman J. Colman,

Commissioner of Agriculture.

5

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-

7

nlating fliers of the valve project on the outside of the apparatus: In
the middle of the valve a needle is welded which occupies the axis of
the cylinder, and which, when the valve is raised, may be lodged in the
aperture with which the stopper of the cylinder is provided. In this
way, when the valve is raised up and the lower orifice unmasked, the
upper orifice is closed by the needle. When, on the contrary, the valve
closes the lower orifice, the aperture of the stopper is uncovered and
allows the liquid to pass out.

C. V. R.

THE SCALE-INSECTS OF THE ORANGE IN CALIFORNIA, AND PAR-
TICULARLY THE ICERYA OR FLITTED SCALE, alias WHITE
SCALE, ALIAS COTTONY CUSHION-SCALE, ETC.

[Address by Prof. C. V. Riley before tbe California State Board of Horticulture, at
its semi-annual session at Riverside, Cal., April 12, 1837, as reported in the Pa-
cific Rural Press, April 23, 1887.]

Afternoon session.

The convention met in the afternoon at the Pavilion. It being cus-
tomary to appoint from the fruit-growers at large two honorary vice-
presidents at each meeting, L. M. Holt, of the Eiverside Daily Press,
and S. O. Evans, of Eiverside, were elected to fill those positions. Mr.
B. M. LeLong, of Los Angeles, was invited to act as assistant secretary.

The organization having been fully effected, Mr. Cooper, the presi-
dent, gave a brief statement of the work of the board since its organ -
ization. He referred to its previous sessions, aud stated that it was the
expressed wish of prominent fruit-growers of Los Angeles that its next
session be held either in San Diego, Santa Barbara, or Eiverside. He
had accordingly, in the hope that the well-known interests of the people
of this section in horticulture would lead to a better attendance than
was sometimes obtained, arranged for the meeting here. The previous
session had brought out valuable information, which was being printed,
and would be distributed. It was necessary that the mass of new-
comers to this portion of the State should be furnished facts which might
save them from making expensive blunders. The insect pests are not
being overcome as could be wished. He referred to the presence of
Professor Eiley, one of the most prominent entomologists in the coun-
try, and stated that he would give us some valuable information at a
subsequent session. He urged co-operation among fruit-growers, and
hoped an effort would be made to modify the effect of the interstate
commerce bill.

The president then introduced Mr. H. J. Eudisill, a prominent hor-
ticulturist of Eiverside, who gave an eloquent and very appropriate
address of welcome.

At the conclusion of this address the secretary read a well-written

and valuable essay prepared by Mrs. H. H. Berger, of San Francisco,

on Japanese fruits.

9

10

At the conclusion of the essay, Mr. Wilcox, of Santa Clara, suggested
that the convention consider the points in Mrs. Berger's paper, and re-
ferred to the high character of our fruits exhibited at Xew Orleans,
making special mention of the persimmons there exhibited. They could
be grown successfully over the larger portion of the State, and were
really a very fine fruit.

Mr. Klee spoke of the fact that most of the Japanese persimmons
were grafted on inferior stock, but that we have a better stock upon
which to graft in the European persimmon, and that with it we may
expect an improvement in the fruit. He had an idea that while the
persimmon would grow well in all sections, it would do better in the
more humid portions of the State. He suggested that it would be well
to experiment with the Japanese oranges in Eiverside. Didn't think
they would grow of large size, but had excellent points in their favor.

Mr. Klee said the loquat could be grafted on the quince, but did well
on its own root. Said the Chinese had better varieties than those
with which we are familiar. This fruit could be dried like the fig.

Mr. Starr, of Lugonia, said the persimmon did excellently in the
sandy soil of his neighborhood, bearing freely and regularly.

Mr. Holmes thought experience in Eiverside had demonstrated the
correctness of Mr. Klee's theory that a more humid climate was prefer-
able for this fruit, although it fruited satisfactorily here.

Tuesday's session.

The convention assembled at 9.30 a. m. The first business on the
programme was the address of Professor Riley on Scale-insects. He was
introduced by President Cooper in a very off-hand but happy and ap-
propriate manner, alluding at some length to the efficient maimer in
which the professor had conducted the labors of his office, in studying
the habits of some of the most destructive insects which have afflicted
the farmer and horticulturist, and in devising ways and means to get
rid of them.

The professor, on taking the floor, very modestly disclaimed the eu-
logy which the president had pronounced, and proceeded at once with
his address, which was full of valuable information, and which, though
quite lengthy, was listened to with the most marked attention through-
out.

Professor Riley said :

Mr. President, Lathes, and Gentlemen : When I left Washing-
ton it was with the intention of resisting all invitations to speak, as I
have been suffering for some time from the effects of overwork and de-
sired quietly to pursue some investigations in relation to insects in-
juriously affecting fruit culture here and at the same time get rest
from exacting office duties. But it was impossible to refuse the urgent
appeal of your president, Ellwood Cooper, to address this meeting. 1
have, however, no formal address to offer you.

11

The subject announced, namely, "Entomology in its Eelation to Hor-
ticulture/7 is one chosen by some enterprising member of your Board,
and is altogether too comprehensive to be dealt with without more time
and more thought than I have had at command. I shall endeavor to
confine my remarks to scale-insects, and particularly to what you know
as the White Scale. This is the insect which undoubtedly most con-
cerns you just now, aud I have an elaborate article upon it now going
through the press at Washington. This, however, would require two
or three hours to read, and I will pass over the purely historical and
entomological details and touch only upon such points as will probably
interest you.

NOMENCLATURE.

There is no doubt whatever about this insect being the Icerya pur-
chasi, of Maskell, and its scientific name is, therefore, fixed.* In refer-
ence to its popular name, there are several in use, and as between
"Australian Bug," u White Scale," and u Cottony Cushion-scale " there is
very little choice, and it is, as a rule, useless to endeavor to change pop-
ular names that have once come into vogue. So far as they can be
changed, however, and with a view of inducing unanimity in the adop-
tion of a single name, it were better to reject all these names and call
it the Fluted Scale. There are many Australian bugs and many white
scales, some of which, belonging to the genus Pulvinaria, equally well
deserve that cognomen. Cottony Cushion-scale is both too long to be
acceptable and would likewise apply to the species of this last genusr
whereas no scale-insect injurious to fruit or other trees, at present
existing in this country, secretes its white, waxy matter in such a per-
fectly fluted mass as this. The generic term, Icerya, if once popular-
ized like Geranium, Phylloxera, &c, has the advantage of brevity and
still greater accuracy.

GEOGRAPHICAL DISTRIBUTION.

Historical evidence all points to Australasia as the original home of
this insect, and its introduction from Australia to New Zealand, Cape
Town, South Africa, and California. Nothing was known or published
upon the species prior to the seventh decade of this century, and it seems
to have first attracted attention almost simultaneously in Australasia,
Africa, and America. The evidence as to whether it is indigenous to
Australia or New Zealand, or to both, is not yet satisfactory. The first
personal knowledge which I had of it was from specimens sent to me in
1872 by Mr. E. H. Stretch, then living in San Francisco, and all the
evidence points to its introduction into California by the late George
Gordon, of Menlo Park, about the year 1868, and probably from Aus-
tralia, on Acacia latifolia.

* This statement is, of course, based on the assumption that Maskell's purchasi is a
good species. It may yet prove to be synonym of sacchari Signoret.

12

More light is, however, yet needed on this point, as in a recent letter
received from Baron von Miiller, of Victoria, he claims that it could not
have been imported on Acacia into this State, as all the Acacias in the
State have been grown from seed. This is a matter upon which I should
like to have definite information froai members of this body, if such
information is extant.

It is at present widely distributed in the State, and a very full ac-
count of its distribution kindly furnished to me by Mr. Matthew Cooke
shows that there are some ten infested districts, namely, six in the coun-
ties of Marin, San Mateo, Santa Clara, Sacramento, Sonoma, and Xapa,
and four in the counties of Santa Barbara and Los Angeles. I find that
it has also obtained a foothold in a few isolated places around San Diego,
from which it may yet be stamped out.

FOOD PLANTS.

A very long list of plants might be enumerated upon which this in-
sect is either found accidentally or upon which it can live more or less
successfully. But the list of plants, especially of trees important to us
for their products, which are seriously affected by it is comparatively
limited, and will include the Acacias, Lime, Lemon, Orange, Quince,
Pomegranate, and Walnut. Some few other trees might be added, and
it is particularly partial to the Eose and the Settle ; but it is doubtful
whether the species could permanently thrive and multiply to an inju-
rious extent on many other trees than those mentioned.

CHARACTERISTICS OF THE INSECTS.

The genus Icerya was founded by Signoret, a French entomologist, in
1875, being based upon the single species, Icen/« sacchari (Guerin). which
lives on sugar-cane in the island of Bourbon. This species and the one
we are now dealing with are the only two species of the genus, and the
diagnosis as given by Signoret, and subsequently elaborated by Maskell,
of Xew Zealand, is incomplete and does not include the characteristics
of the male.

In the report already alluded to I have given a very full character-
ization of the species in all conditions and stages, but the only facts
that I need draw attention to on this occasion are, first, that the female
undergoes three molts and the male two; i. e., each has one more
stage than has hitherto been recognized by entomologists and ob-
servers ; secondly, that it differs from all other members of its family
(Coccida?) in its extended powers of locomotion iu most of its stages;
in its extreme hardiness or power of surviving for a given period with-
out food, and in its polyphagias habit, or the ease with which it accom-
modates itself to so great a variety of plants. These are the three char-
acteristics which most concern you as fruit-growers, and which make it
one of the most difficult species to contend with.

13

MODE OF SPREAD AND DISTRIBUTION.

All young scale-insects are quite active when they first hatch, and
most of them at this time are extremely small, and when very thick
upon a tree, instinctively, or at least very easily, drop from the terminal
twigs and branches. Their specific gravity at this time is so light that
they are easily wafted with the wind in their descent. This general
truth applies with equal force to the Icerya, which is readily carried
from tree to tree and from orchard to orchard by the agency of wind,
by running water, or by birds or other insects. Another local means
of transport not to be ignored, is upon the clothing of persons engaged
in cultivating, upon packages, and upon all implements used, whether
in cultivating or harvesting the crop. This particular species also has
quite a habit of crawling over the ground, and its local spread is very
materially enhanced thereby.

It is carried long distances, however, chiefly by high winds, birds,
and commerce, and its introduction from one continent to another has
undoubtedly been effected by the latter method upon young trees or
cuttings.

NATURAL ENEMIES.

No bird is known yet to attack this iusect in California, and but one
is mentioned even in Australia, and that upon very slight evidence Of
predaceous insects, a species of Lace-wing (genus Chrysopa) has been
observed to feed upon it, as also the Ambiguous Lady-bird (Hippodamia
ambigua). The larva of a little moth, which I have described as Blas-
tobasis iceryceella, is also known to feed upon the eggs. Among the
Heteroptera, or true bugs, quite a number have been found upon the
trees infested with the insect, but none have yet been noticed to feed
upon it. The most important of its insect enemies are a species of ear-
wig not yet identified, and a number of mites not yet carefully studied.

Of true parasites, none have hitherto been reported, whether in Aus-
tralia, Africa, or America, but I am glad to announce that two speci-
mens of a minute Chalcid-fly have been bred by me from specimens
around Los Angeles, and will be described by my assistant, Mr. L. O.
Howard, who makes a specialty of the family, under the name of Isodro-
mus iceryw. The genus is new to our fauna, and the probability is that
this little friend was introduced from Australia with its host.*

PREVENTIVE MEASURES.

Most of the members of this society are doubtless aware that for
some four years I was conducting a series of very careful experiments
with a view of controlling the scale-insects and other insect pests that
injuriously affect the orange trees in Florida. This work was carried

*Mr. D. W. Coquillett informs me that be has since reared a Proctrotrupid, proba-
bly of the genus Cosmocoma, from tbe male pupa.

14

on through the instrumentality of Mr. H.G. Hubbard, and the Depart-
ment of Agriculture has published a special report prepared by him
upon this subject. All that is said in that report in reference to the
value of preventive measures against the scale-insects of that part of
our country will apply with equal force here in California.

The value of cleanliness; of thorough cultivation; of pruning judi-
ciously so as to get rid of all dead wood, open the top of the trees to the
light and to the sun, and facilitate the spraying of the trees need scarcely
be emphasized. There may be some difference of opinion as to the
value of pruning, while different kinds of pruning, or no pruning, will
have their advocates here as the}' have had elsewhere. The orange
makes, naturally, a very dense head, and in the moist climate of Flor-
ida, where they have a much larger average of shade, cloudiness, and
moisture than you have here, judicious pruning has all the advantages
stated, and whether needed or not in California for the purpose of more
fully ripening and maturing the fruit, I am quite satisfied from what I
have seen that it is just as much needed to facilitate proper spraying of
the trees and to prevent overproduction.

Some years ago, and prior to the discoveries resulting from the in-
vestigation in Florida just referred to, the inadequacy of most washes
caused many of the orange-growers of that State to cut back their trees
most rigorously, leaving little more than the main trunk, in the hope of
thus being able to kill out or exterminate the scale-insects that troubled
them there. I fiud that many of your orange-growers are going through
the same sad experience and resorting to the same sad means. It is a
pity to find men thus re-enacting a farce which has been proved in an-
other part of the country to be quite unnecessary. Such wholesale lop-
ping of limbs requires much labor, and even with the greatest care,
which is seldom bestowed upon it, the tree receives an immediate and
material injury, and is destined to suffer still more in years to come.
Moreover, this radical means often proves futile so far as the results
aimed at are concerned, and unless the greatest precaution is taken to
properly cover and heal the stumps and to absolutely kill all the insects
upon the remaining trunk, as well as those upon the severed branches
and the ground, the new growth will soon be as effectually infested as
was the old. Many of your own growers have thus lopped or are now
cutting back their trees in a verv blind way and without the precautions
here indicated, on the popular but erroneous supposition that without
such precautions they will get rid of the troublesome scales.

The value of shelters in theform of surrounding trees and wind-breaks
is, I am sure, just as appreciable here, if not so much to protect from
frost and winds, fully as much to protect from infection from scale-in-
sects. A row or tall hedge of coniferous trees, such as your cypress,
upon which the scale-insects will not thrive— or, better still, a belt of
the same — will often serve as an effectual screen to prevent the young
insects from being carried from an infested to an uuinfested grove.

15

Preventing its Introduction. — But, before passing this subject of pre-
ventive measures, I must not omit the importance of any effort looking
to preventing the introduction of this insect from one section of the
country or from one neighborhood to another. No insects so easily
bear transit as these scale-insects, and it is eminently true of this par-
ticular leery a.

All the worst species from which they suffer in Florida have been in-
troduced from abroad. Their Long Scale (Mytilaspis gloverii) was in-
troduced about the year 1835, their Chaff Scale (Parlatoria pergandii)
from Bermuda some twenty years later, aud their Eed Scale (Aspidio-
tnsficiis) from Havana in 1879.

^Ve have already seen how this Icerya was introduced into your
State from Australia, and the next worst species which you have to deal
with, namely, your Red Scale (Aspidiotus aurantii), was likewise intro-
duced, so far as the evidence goes, from the same country.

To enumerate merely the different species of insects destructive of
your fruit interests that have been introduced from other parts of the
country or from other parts of the world would consume too much time,
and I cannot attempt to do so. But I would lay stress upon this con-
viction, which has forced itself upon me after a pretty extended experi-
ence in all parts of the country, namely, that however much you should
encourage all co-operative efforts to prevent such transferring and
spread of iujurious pests, they cannot be fully exterminated when once
they obtain a foothold, and in the end each individual fruit-grower
must depend on his own efforts.

REMEDIES.

It follows without saying that what we should seek in any direct
remedy is, first, perfect killing power, or, to be more exact, perfect in-
secticide quality associated with harmlessness to the tree; second,
reasonable cheapness.

Different Washes. — I will not detain you with any general remarks on
the subject of insecticides, because it has received full attention in my
official reports. Dry insecticides have been found, in the main, unavail-
able here, and we must depend upon washes or materials in solution
that may be sprayed upon the tree. Here, again, I would remind you
of the careful and extended experiments made by Mr. Hubbard in the
orange groves of Florida with a view of solving the important question
as to what is, on the whole, the most satisfactory liquid application,
cheapness and efficiency considered. Carbolic acid, creosote, sulphur-
ated lime, silicate of soda, sulphuric acid, sulphuret of iron, bisulphide
of carbon, and many other materials have been thoroughly tried, as well
as whale-oil soap, potash and soda lye and their various combinations ;
but in the end nothing proved equal to emulsified kerosene. Whale-oil
soap is an excellent wash for destroying some insects upon some plants,
but it fails to kill the e^rgs of our scale-insects, so that, however good it

1G

may be for scrubbing the trunks ami branches of a tree, I cannot con-
scientiously urge it as, on the whole, satisfactory, particularly as it is
known to stain the fruit, and because of the many different grades,
varying in their effect and in their value, which are upon the market.
Potash and soda lye injure the tree more than kerosene does and do not
destroy the insects as well, admirable though they are as washes in
weaker solution for some other purposes. The action of sulphurated
lime (flowers of sulphur boiled in milk of lime) is very similar to that
of caustic potash.

Notwithstanding the kerosene emulsions, in proper proportions, have
proved so satisfactory against the scale-insects of the Orange in Flor-
ida, the}' have, as a rule, failed to win the good opinion of the orange-
growers in California. I have always believed the want of success in
this State with the kerosene emulsions was due to imperfect preparation
of them, or to imperfect application. I was inclined to give some cre-
dence to the theory advanced by my old-time friend, Prof. E. W. Hil-
gard, who is so keenly alive to everything that interests you, and whose
services have been so invaluable to the agriculture and horticulture of
the State, namely, that the dryness of the atmosphere in California
induced a more rapid evaporation of the kerosene, which may partly
account for the difference in experience between the Atlantic and Pa-
cific. For these reasons I had long desired to make a series of ex-
periments in California, and finally, last year, did have such a series
carried on by Messrs. D. W". Coquillett and Albert Koebele. It were
difficult to find in the whole State two gentlemen combining in the
one instance more care and reliable entomological capability, and in
the other more industry, earnestness, and enthusiasm, and this I say
without desire to flatter, but as evidence that their experiments, so far
as they went, were trustworthy — in fact, I may say, the most careful
and thorough that have hitherto been made. These experiments ex-
tended over a period of three months in the spring and three months in
the autumn, and the detailed reports which these gentlemen have made
will be published in connection with my forthcoming annual report.
They show that the kerosene emulsions must still be placed at the head of
the list of washes, not only for ordinary scale-insects, but for this Icerya
or Fluted Scale. Among the different substances thoroughly experi-
mented with were caustic potash, caustic soda, hard and soft soaps, to-
bacco, sheep dip, tobacco soap, whale-oil soap, vinegar, Paris green,
resin soaps and compounds, and so on. It is impossible to give even a
digest of the very many experiments, and the varying results obtained
with the different washes. It suffices to say that the kerosene emulsion
diluted with from eight to ten parts of water was found to kill all the
eggs as well as the old females, and that. even when used still stronger,
it left the tree uninjured. Mr. Coquillett reports with reference to the
much-praised caustic soda, that it has no effect on the eggs of this scale
even when applied so strong as to burn the bark and kill all the leaves.

17

Similarly, the whale-oil soap does not kill the eggs directly, though it
may harden the egg-mass so as to prevent the hatching of a large pro-
portion of young larva3.

Resin Soaps. — Mr.Koebele experimenting through August, September,
and October, found similarly good results from the kerosene emulsion,
but that the crude petroleum, although much cfieaper, was more apt to
injure the tree. His attention was, however, directed mainly to the
preparation of resinous soaps and compounds on account of their greater
cheapness. He succeeded in making a number of these mixtures which,
when properly diluted, need not cost more than one-half to one cent
per gallon and which produced very satisfactory results, killing the
insects or either penetrating or hardening the egg masses so as to pre-
vent the hatching of the young. One of the most satisfactory methods
of making a resin soap is to dissolve one pound caustic soda in 1J gal-
ions water to produce the lye ; then dissolve 2 pounds resin and one
pound tallow by moderate heat, stirring in gradually during the cook-
ing one quart of the lye, and then adding water until you have about
22 pints of a brown and thick soap. This will make 44 gallons of wash,
costing less than one-half cent per gallon.

There is some slight difference between the experience of Mr.Koebele
and Mr. Coquillett as to the value of soap washes, and the greater suc-
cess which the former had with them as compared with the latter was
probably due to the fact that his experiments were made during the
dry or rainless season. The great point of interest, however, in these
experiments is that they confirm in a remarkable manner the experience
had in Florida. And I think you will agree with me that they justify
the opinions which I have expressed in official writings. Such observa-
tions as I have been personally able to make during my brief sojourn
among you have greatly served to confirm me in those opinions, and
while the resin soaps experimented with by Mr.Koebele are a valuable
addition to our insecticides for the scale-insects, I find the experience
in Florida repeated here, and all the more satisfactory washes have
kerosene as their effective basis. There has been, however, a very
great waste in applying it, and it is in this direction that reform is
most needed.

The fact cannot be too strongly urged that in the case of this Icerya,
as of most other orange-feeding scale-insects, it is practically impossible,
with the most careful and thorough spraying, to reach every one of the
myriads on the tree. Some few, protected by leaf-curl, bark-scale, or
other shelter, will escape, and with their fecund progeny soon spread
over the tree again if left unmolested. Hence, two or three sprayings,
not too far apart, are far preferable to a single treatment, however
thorough. And this is particularly true of the pest we are considering,
which lives on so many other plants, and which in badly infested groves
is frequently found crawling over the ground between the trees.
404— Bull. 15 2

18

Value of Kerosene Emulsion. — It is now the custom to use the time of
a team and, say, two men for fifteen or twenty minutes or more, and 30,
40, or 50 gallons of liquid on a single medium-sized tree. Id this way
the tree is sprayed until the fluid runs to the ground and is lost in great
quantities, some growers using sheet-iron contrivances around the base
of the tree in order to save and re-use the otherwise wasted material.
Xow, however much this drenching may be necessary, or has come into
vogue, in the use of soap, and potash and soda washes, it is all wrong,
so far as the oil emulsion is concerned, as the oil rising to the surface
falls from the leaves and wastes more, proportionately, than the water.

The essence of successful spraying of the kerosene emulsion consists
in forcing it as a mist from the heart of the tree first and then from the
periphery, if the tree is large, allowing as little as possible to fall to the
ground, and permitting each spray particle to adhere. It is best done
in the cool of the day, and, where possible, in calm and cloudy weather.
There has been no morning since my sojourn among you that I have seen
the sun rise in a clear sky. Cloudiness has prevailed for some hours
after dawn, and iu this regard you are favored, as this would be the
time of day, of all others, to spray. Proper spraying should be done
with one-fifth of the time and material now expended, or even one-tenth
of that which I have seen wasted in some cases, so that three sprayings
at proper intervals of from four to six weeks in spring and summer will
be cheaper and far more satisfactory than one as ordinarily conducted.
In this particular neither Mr. Coquillett's nor Mr.Koebele's experiments
were entirely satisfactory, as I was too far from the field to permit of
the detailed direction necessary.

I cannot emphasize the fact too strongly that it is practically impos-
sible to eradicate, by any system, every individual insect and egg upon
a tree in one spraying. It is almost futile to attempt to do so.

improved Wash recommended. — Let us now see whether the kerosene
emulsion, pure and simple, can be improved upon by the addition of
any other material. It is plain to be seen from the circulars and docu-
ments, both official and unofficial, that have been published in the
State and distributed among you, that, in many cases, the proper use
of kerosene has been entirely misunderstood. Having already seen
that it destroys the eggs of Icerya only when used in the ratio of one
part of kerosene to about seven or eight of the diluent, it follows that
any lesser amount will give less satisfactory results. Moreover, it is
extremely important to prepare the emulsion properly. This has usu-
ally been done by the use of milk or of soap, because they are cheap
and satisfactory. Raw eggs and sugar, and other mucilaginous sub-
stances may be used. Experience has shown that the best pro-
portions are two parts of the oil to one of the emulsifying agent,
whether milk or soap, i. c, for instance, two gallons of the oil to one of
milk or one of the soap-water made by dissolving half a pound of soap
in one gallon of water. So long as these proportions are maintained

19

a large quantity can be emulsified as rapidly as a smaller quantity, and
violent agitation through a spray-nozzle at a temperature of -100°, and
as frequently described in my reports, gives the quickest results.

Take, for instance, the mixture recommended by your county board
of horticultural commissioners. You will find that with the soap and
wood-potash there are twenty-five parts of the diluent to one of the kero-
sene recommended, and there is every reason to believe that the kerosene
in this wash might just as well be thrown away, and that it adds com-
paratively little, if any, to the efficiency of the wash, at least for the
fluted scale. If, on the contrary, we could add to the ordinary emul-
sion any materials that would give greater adhesiveness, such an addi-
tion will prove an advantage. Such we get, to some extent, in the
soap emulsion, for which reason it has a slight advantage over the milk
emulsion. And after examining the trees treated with resin washes, I
am strongly inclined to recommend that these resin washes be used as
the diluent to the soap emulsion made after the usual formula. Some-
thing similar was tried some years ago by one of my agents in Florida,
Mr. Joseph Voyle, who used fir balsam in place of resin, in connection
with the oil emulsion, and obtained most satisfactory results. A cer-
tain amount of dextrine, or, yet better, flour, if mixed with the wash,
would prove valuable for the same purpose.

Again, if permanency can be given to the effect of a wash so that
the few insects escaping the first application, or which would hatch out
thereafter, would succumb, such addition would be invaluable ; and
though the arsenites are, as a rule, effective chiefly against naandibu-
late insects, or those which masticate their food (in other words,
although the action of these poisons is mainly through the stomach),
yet I happen to know from experience that they have also a direct
effect by contact. Therefore I recommend, with considerable confi-
dence, that in this dilute kerosene emulsion there be added a small
proportion of arsenious acid, say from 2 to to 3 ounces to every 50 gal-
lons of wash. This arsenious acid may be prepared and added in va-
rious ways. Probably one of the simplest would be to take half a
pound of arsenic to half a pound of sal-soda, boil this in one-half gal-
lon of water until the arsenic is dissolved, and mix this with about 100
gallons of the diluted emulsion. A quarter of a pound of London pur-
ple to 50 gallons of the diluted emulsion, or even a still greater amount,
would, perhaps, serve the same purpose and be less likely to injure the
tree.

I am aware of the danger of making recommendations that have not
yet had thorough trial, but I have already made a few limited experi-
ments (and intend making more) which would seem to justify these, and
at all events if care be taken not to use too large a quantity of the ar-
senic no harm will result from it, either to the tree or to those who use
the fruit.

20

Kerosene is not so cheap as the resin compounds, nor as some of the
soap and lye washes, but it has this great advantage, that it can be
used in much less quantity. It permits a great reduction in the amount
of material and the cost of labor. At the rate of 20 cents per gallon
wholesale, the effective wash will cost 2h cents per gallon, and from
one to two gallons are sufficient, if properly sprayed, on a medium-
sized tree.

SPRAYING APPARATUS.

Just as there is a great wastage of time and money in drenching a
tree with kerosene emulsion, so the spraying nozzle most in vogue with
you is also somewhat wasteful. That most commonly used is the San
Jose nozzle, in which the water is simply forced through a terminal slit
in a narrow and rather copious jet of spray. It is the force and direct-
ness of the spray which gives this nozzle its popularity under the mis-
taken spraying notions that prevail, and to this I should probably add
the fact that, being a patented contrivance, it is well advertised, and
on the market, for somehow or other people rarely value a gift as much
as what they buy, and too often rate value by price. The Cyclone noz-
zle, or Eiley atomizer, as it is called in France, which has proved so sat-
isfactory in the East as well as to my agents at Los Angeles, has scarcely
had such trial among you, so far as I have been able to see, as to prop-
erly impress its advantages. That originally made and sent out by the
late G. N. Milco, of Stockton, was patterned in size and form after one
which I sent him, and which was designed to spray from near the sur-
face of the ground.

What I would use for the orange grove, or for trees, is a buuch of
nozzles of larger capacity, the size of the outlet to be regulated by the
force of the pump. I have witnessed all forms and sorts of spraying
devices, and while there are many that are ingenious and serve a use-
ful purpose, I can safely say that there is no form which will produce a
spray so easily regulated and altered to suit different conditions, and
which is so simple and so easily adjustable to all purposes. Since
among you I have endeavored to get a bunch nozzle, such as I would
recommend, made at Los Angeles, and the difficulties I have had in get-
ting it made properly illustrate, perhaps, some of the reasons why this
nozzle has not become more popular on this coast. All the parts must
be well fitted ; the inlet must be tangential and the outlet so made as
not to overcome the whirling or cyclonic action of the water. The
breadth, directness, force, or fineness of the spray are all regulated by
the form and size of the outlet, and if a thick cap be used it must be
gradually countersunk on both sides until the thickness at the outlet
does not exceed one-sixteenth of an inch or less. A bunch of four noz-
zles, one arranged so as to have the outlet distal or from the end of the
piping, which may be ordinary gas-pipe, and the other three in bunches,
so that the outlet is at nearly right angles, each about an inch below

21

the other, and so placed that they are one-third the circumference of
the main pipe apart, will be found, I think, most serviceable in your
groves. Such a bunch working from the center of an ordinary-sized
tree will envelop it in a perfect ball of mist.

For tall trees a more forcible stream might be had from the end by
substituting an ordinary jet with a wire extension. This is a recent
device first brought to my attention by Mr. A. H. Nixon, of Dayton,
Ohio, and for sending a fine spray for a great distance it has advan-
tages. It is simply an extension screwed over an ordinary nipple, the
end of the tube being covered with wire netting, which breaks up the
liquid forced through it. The brass nipple should be about one inch
in length, the perforation very true and varying in diameter according
to the force of spray desired. The nipple screws on the discharge pipe,
and upon a shoulder threaded for the purpose is screwed a chamber or
tube about one inch in diameter and three inches long, to the outer end
of which is soldered a piece of wire gauze varying in size of mesh to
suit the force of pump and the size of aperture in nipple.

Finally, if a service of blind caps and several sets of cyclone nozzle
caps of varying aperture are kept on hand, the spraying may be ad-
justed at will to condition of wind, size of tree, &c.

Your worthy president has very well remarked that what we want is
not generalization, but hard facts and experience presented in the
simplest and briefest manner. If I have dealt somewhat with princi-
ples rather than with details, I shall look for your excuse in the fact
that extended experience presents such a multiplicity of details as to
warn me from entering into them.

FUMIGATION.

Fumigating trees will always have, cceteris par thus, some disadvantage
as compared with spraying. The mechanism is more cumbersome ; the
time required for treatment and the first cost in making preparation
greater, and these facts will always give spraying the advantage with
small proprietors and those who are dealing with young trees. Sulphur
fumes have been tried, but they burn the leaves and injure the tree.
Tobacco smoke and vapor fail to kill the eggs. Ammonia is excellent,
but fails to kill all, though I have known the most beneficial results from
the ammonia arising from sheep manure used as a fertilizer in apple
orchards. Bisulphide of carbon has been tried, and with great care in
getting the right quantity its vapor will kill the insects without killing
the tree ; but its application requires too much time and is fraught with
more or less risk to man. This is equally true of cyanide of potassium
and of other substances the vapors from which are known to be very
deadly to insect life. It will be difficult, therefore, to find a mode of
fumigating that will be harmless to the tree and deadly to the insects,
and at the same time as rapidly and easily applied as a spray.

22

Many of yon already know that Mr. Coquillett, in connection with
Mr. Alex. Craw and Mr. Wolfskill, of Los Angeles, have /or some time
been conducting a series of experiments which lead them to believe that
they have discovered a gas which possesses the requisite qualities. The
trees which I have examined that have been treated with this gas, both
there, at San Gabriel, and at Orange, lead me to the conclusion that
they are fully justified in this belief, ami several ingenious contrivances
have been perfected in Los Angeles County which give promise of great
utility and feasibility. Whether the trees are left uninjured, it is per-
haps premature to say. That they are affected is evident 1:1 some cases,
and what the ultimate effect will be time alone will decide. Let us all
hope that the promise of this gas will be abundantly fulfilled. Let me
add, however, that even if it be found that no solitary insect or egg will
escape treatment with this or any other gas, fumigation will yet no
more fully exterminate or free the orchard than the proper spraying of
the kerosene emulsion, but, for the reasons already stated, will have t<>
be repeated. In other words, one application, however perfect in de-
stroying insect life, cannot and should not be depended on. The disad-
vantage about this gas in my estimation is that it is kept so far a se-
cret. We cannot perhaps blame the gentlemen for endeavoring to re-
alize something out of what they consider a valuable discovery that
will compensate them for the time they have devoted to the purpose ; but
I am always suspicious of secret or patent insect remedies. My friend,
Mr. Coquillett, perfected this gas after his employment by the Depart-
ment of Agriculture ceased. But it is a general truth that the moment
any person or persons become interested in a patent or in any remedy
they desire to control, from that moment their judgment can no longer
be depended on as to the value of other remedies.

I have been asked why Mr. Coquillett was not continued in the serv-
ice of the Department for a longer period, and it is perhaps due to the
fruit-growers of California and to him to explain why the experiments
which he began were interrupted. It had been my desire to have two
agents permanently located on the Pacific coast to carry on the work
of my Division here, for I have long felt that your fruit interests, to say
nothing of the other agronomic interests of the State, demanded sucli
recognition at the hands of our National Government. It so happens
that in my desire to aid other investigations that bear upon the promo-
tion of agriculture, I took part in urging the creation of a Division of
ornithology and mammalogy for thepurposeof investigating the habits
of birds and mammals so far as they affect agriculture and horticulture.
The friends of ornithology were successful in getting that Division cre-
ated, but were unable to get an appropriation to carry on the work, ex-
cept by taking it out of the appropriation for the Entomological Divis-
ion; and during my absence from the country last June, and after all
my arrangements had been made for work on the Pacific coast on the
basis of the appropriation bill passed by the House of Representatives,

23

the amount was cut down in the Senate and part of it given for the or-
nithological work, thus requiring the discharge of a number of those
already engaged, and restricting the work of the De partment in ento-
molog3\

BANDAGES AROUND THE TRUNK.

There is always danger that a tree once sprayed or disinfected will
get reinfested from the insects that have not been reached upon ad-
jacent plants or upon the ground, and which in time may crawl upon
the trunk. Any of the sticky bandages used for the canker-worm will
check this ascent, but when the sticky material is placed directly on
the trunk it may do more harm than good. It should, therefore, be
placed upon strips of tar paper or other stiff paper, tied by a cord around
the middle, the upper end flared slightly outward, and the space be-
tween it and the trunk filled with soil to prevent the young insects from
creeping beneath. Cotton should not be used for this purpose, as birds,
for nesting purposes, carry away particles of it which may contain the
young insects and may thus help to disseminate them.

LEGISLATION.

Xext to the destructive locusts which occasionally ravage our grain-
fields no other insect has perhaps been more thoroughly legislated
against than this Icerya in California. Indeed, the manner in which
the people of this State have taken hold of this insect question and
have endeavored by all legislative means to enforce such action on the
part of fruit-growers as best subserve the interests of the whole State,
is highly commendable. Yet, while much good has undoubtedly re-
sulted, the laws have too often proved inoperative, either through the
negligence or ignorance of those appointed to execute them, or still
more often through the indifference or opposition of individual growers,
or unwillingness of the courts to enforce the laws with vigor. And
while the greatest co-operation should be urged, and, if possible, en-
forced, in battling with these insect pests, yet, so far as this particular
species is concerned, no human endeavor can now exterminate it from
the country. It has come to stay, and nothing has more fully forced
itself upon my conviction than that, in the end, with all our laws, each
orange-grower must depend upon his own exertions. It is, therefore,
fortunate that the pest may be controlled by such individual exertions.
While, however, we must admit that it is beyond our power to fully
eradicate it from those districts in which it has obtained a foothold, the
case is quite different when it comes to restricting its spread, and it is
in this direction that wise legislation, and the strict carrying out of the
legislative measures you have adopted, or may adopt, will be productive
of much good.

Eecent history has furnished very good evidence of the power of
stringent measures adopted by governments, whether to prevent the

24

introduction of an insect pest or to stamp it out when first introduced
and before it has acquired a strong foothold. Several European nations
have, in this way, averted, so far, the Grape Phylloxera, and the Ger-
man Government, on one occasion at least, effectually stamped out our
Col orado Potato-beetle, which became established in a restricted locality.
The danger which threatens orange-growing districts in this State
not yet affected, as well as the orange belt on the Atlantic seaboard, is
great, and we cannot too earnestly appeal to the authorities that be for
means to employ still greater vigilance to avert it.

RIVERSIDE.

What a relief it is to get from a scale-infected region, with the at-
tending evils of blighted and withering growth, smuttiness, and unmar-
ketable fruit, into a neighborhood yet exempt from these pests, like this
enterprising locality in which you meet! What a joy in contemplating
by contrast the bright and cleanly aspect of the trees ! And what is
there more beautiful in nature than a perfect orange grove at this sea-
son, and yet untainted by Coccid or Aphid, or other insect enemy ? In
all my travels I have nowhere felt nearer the ideal Garden of Eden than
in some of your lovely valleys, yet unvisitedby these destroying atoms.
The profusion and perfection of fruit and flower, the elysian character
of the landscape, the genial sun — all appeal to the higher esthetic feel-
ing in man, and one is moved to enthusiastic contemplation and admira-
tion of the glories of nature and the bounties of Hea ven under such
favoring conditions !

STATE ENTOMOLOGIST.

You know better than I do how your laws have acted in the past and
are acting now, and how far your State inspector and your different
county inspectors have succeeded.

But, before passing this matter of legislation, I should be derelict in
my duty if I did not urge upon you the value of one form of legislation
which has not yet been tried. Without abating one iota the work al-
ready being done, whether by individuals or boards, it does seem to me
that if you had a State Eutomologist, i. e., an officer appointed to devote
his entire time to this subject of economic entomology in the State.
much additional good might be acco mplished, provided he were properly
supported and given the means to carry on his work effectually. You
should not commit the same error that has been committed by some of
the Eastern States, in which the cultivators of the soil have desin d to
have such a State entomologist appointed. In three cases which I now
have in my mind there has been quite a disposition on the part of the
legislature to pass a proper bill, but it has failed in each ease because
of the conflicting interests which aimed to control the office. Either
the State Board of Agriculture, or a State Horticultural Society, or a
State Agricultural College, or some State university, or some other

25

State institution, desired to have the honor and the privileges pertain-
ing to the office, and, between them all, failure has resulted. I should
like to see California with a competent State Entomologist appointed,
under a bill carefully drawn up providing his duties, by the governor,
upon recommendation of the professor of agriculture in your State uni-
versity, and the president of such other State horticultural and agricul-
tural bodies as may exist. In this manner the interests of all these
bodies might be considered, and the State could not, in my judgment,
make a more profitable investment than in the creation of such an office.

IMPORTATION OF PARASITES.

It has doubtless occurred to many of you that it would be very desir-
able to introduce from Australia such parasites as serve to keep this
fluted scale in check in its native laud. We have already seen that
there is one minute parasite which has, in all probability, been brought
over with it from Australia, and there is no question but that it is very
desirable to introduce any such of its enemies and parasites as can be
introduced. This State— yes, even Los Angeles County — could well
afford to appropriate a couple of thousand dollars for no other purpose
than the sending of an expert to Australia to devote some months to
the study of these parasites there and to their artificial introduction here.
But the agent must be an expert entomologist, and his selection should
be left to some competent authority. The result for good, in the end,
would be a million-fold, and I have no fear but what you, as orange-
growers, will appreciate the force of this statement. I would not hesi-
tate, as United States Entomologist, to send some one there with the
consent of the Commissioner of Agriculture, were the means for the
purpose at my command ; but unfortunately, the mere suggestion that
I wanted $1,500 or $2,000 for such a purpose would be more apt to cause
laughter and ridicule on the part of the average committee in Congress
than serious and earnest consideration, and the action of the last Con-
gress has rendered any such work impossible by limiting investigation
to the United States.

REMARKS CONFINED TO THE ORANGE.

Let me, in closing, lay stress on the fact that I have, in all that has
been said relating to remedies, had reference solely to the orange and
the scale insects affecting it.

The Fluted Scale is undoubtedly the most difficult to master, and the
means I have recommended against it apply equally to your other
orange scales, as experiment has already demonstrated. Tour Red
Scale, in some respects even worse than the Icerya, and of which I
should like to say something in detail did time permit, succumbs to it.
But when it comes to the treatment of deciduous trees, much that I
have said will not apply, and each tree needs separate consideration
and is affected differently by different washes.

26

PROSPERITY VS. INSECT PES'] s.

In passing from place to place since I have been in the State, and
more particularly in visiting the different parts of Los Angeles Comity,
I have been struck with the wonderful activity every where manifest in
real estate. Laud is " booming w in all parts of the country, but no-
where has it reached such proportions, it seems to me, as right here in
this part of California. There does not, at first, seem to be much con-
nection between the real estate boom and the scale-insects of the
Orange. But I am quite sure that the rapidity with which your orange
orchards have been and are being converted into town blocks and
town lots has a marked influence on the spread and increase of these
scale insects; for no sooner does the owner of a grove subdivide and
sell it than the different new owners allow it to u run to grass,** so to
speak, and for miles around all your thriving and growing centers of
population may be found neglected orchards upou which the insects
are reveling and multiplying and scattering into those which are more
carefully cultivated. To this cause is, in my judgment, due very much
of the rapid reinfesting of these cultivated orchards, so that your insect
troubles are, m a measure, connected with your unp recedented growth
and prosperi ty.

NOT AX UN3IIXED EVIL.

Finally, let me say, before taking my seat, that your scale insects are
not an unmixed evil. With your lovely climate, rich and varied soil,
and the many other advantages which your beautiful country possesses
for the cultivation of the orange and most other fruits, the business
would soon come to be overdone and rendered unprofitable, could even-
one, before plauting his trees, feel sure of an abundant and fair crop
without having to contend with difficulties. Lender these circumstances,
it seems to me that even the dreaded scale-insects, by driving the thrift-
less to the wail and giving the careful and intelligent man who persists
in destroying and defeating them better prices for his product, may,
after all, prove a blessing in disguise. One thing is sure, it is pure folly
to talk of giving up the battle and abandoning the field to these, your
tiny foes. There is no insect that is invulnerable, or that we may not
overcome, if we but attack it at the right time, in the right place, and
with proper means and ability. You will, ere long, feel yourselves mas-
ters of the situation, and if what I have said will aid in ever so little
to give you the victory I shall feel abundantly rewarded. I have already
occupied more of your time than I intended to, and though much is left
unsaid, even about this single insect, I must close in orderto leave time
for discussion. In doing so, permit me to congratulate you as a Board
for the good work already done, and to prophesy that in future years
when the fair and unrivaled fruit of this coast shall have multiplied be-
yond the most sanguine vision of any of us. and have found its way in
one form or another to consumers in all parts of the world, the people
of California will gratefully remember the work you instigated and the
battles vou fought. Ladies and gentlemen, I thank you.

NOTES ON ICERYA-ITS PROBABLE ORIGIN THE ISLANDS OF BOUR-
BON AND MAURITIUS.

C. V. Riley hi Pacific Rural Press, June 11, 1837.

I have just read with a great deal of interest the letter of W. M. Mas-
kell to State Inspector Klee, in your issue of the 7th instant. This letter
really brings up quite an important question, so far as our White or Fluted
Scale is concerned. In an article in my forthcoming report, as United
States Entomologist, of which I have sent you advanced page proofs,
I have, without question, assumed that Icerya purchasi Maskell was a
good species and distinct from I. saccliari Signoret, because Maskell,
in his second article on the former species (Trans. New Zealand Inst,
for 1883, page 140), after an examination of specimens of I. saccliari,
sent him by Signoret, says that he finds the " Mauritian species un-
doubtedly and markedly distinct." This letter to Mr. Klee brings up,
however, the whole question of the accuracy of his determination. He
admits that he has never seen Sign ore t's I. saccliari alive. The only
differences which he made in 1883 between 1. saccliari and I. purchasi
are as follows : "J. saccliari does not seem to form an ovisac with longi-
tudinal grooves, nor does the body of the insect, although somewhat
hairy, show the great tufts of black hairs and the curious projecting
glassy tubes springing from large brown coroneted bases which are
marked features of I. purchasi. The number of circular spinneret ori-
fices are much smaller in the Mauritian insects."

Now Signoret knew only two stages, the full-grown female and the
newly hatched larva, while Maskell gave careful descriptions of the
egg, the young larva, the second stage, and the full-grown female, but
had not seen the male larva, cocoon, or adult. It is for this reason that
I have given a very full characterization of the species in the article
already alluded to.

Signoret's description, so far as it goes, applies thoroughly well to I.
purchasi in some of its forms. His female had not formed the cottony
or tinted-egg covering, at least he makes no reference to it. His figure,
while showing a short truncated mass, does not indicate the flirtings
because the few lines upon it are evidently intended by the artist for

27

28

the long, fine, glassy hairs. Maskell, following Signoret's description,
rightly says that sacchari "does not seem to form an ovisac with longi-
tudinal grooves." But Signoret himself says that sacchari, in the
island of Bourbon, "is confounded with Lecanium (jaster alpha, under
the name of louse-with-the-white-pocket." Whether Signoret assumed
such confounding by the islanders because of erroneous supposition
that this sacchari had no ovisac, or whether the islanders designate both
the Lecanium and the Icenja under the characteristic vernacular, is not
plain from the language, and is immaterial. On the principle of unity
of habit in the same genus, I feel morally sure that Signoret's Icerya
must produce her eggs in such an ovisac, and the Bourbonese are doubt-
less well aware of the fact, otherwise they would not so indicate it or
confound it with Lecanium. We are justified in assuming that the
female which my friend Signoret described and figured had only just
begun forming its sac, and that its ilutings had become effaced and the
secretion unnatural in appearance. MaskelFs second reason, viz, that
sacchari "does not show the great tufts of black hairs and the project-
ing glassy tubes," will also lose force from the facts that Signoret par-
ticularly describes these glassy tubes as " long filaments, waxy, very
fine, delicate, transparent," and that these tufts of black hairs are ex-
tremely variable in quantity, sometimes making the insect look quite
dark and bringing out in strong relief the few smooth, orange-red or
brick-red elevations, and particularly the series of about twenty-two
around the border ; at other times being so scarce that the insect has
an almost uniform reddish-brown appearance.

It would appear, therefore, that, notwithstanding the differences in
Signoret's and Maskell's characterizations, there is room yet for grave
doubt as to the specific difference in the two insects, especially as upon
restudying Signoret's description it accords in every other particular
with I. purchasi.

You will pardon me, I know,, for going into these technical details, be-
cause it is evident that the solution of these questions has a very im-
portant bearing. My own impression now is that future investigation
will prove that the two insects are identical. The truth will in time be
ascertained by getting all the different stages of sacchari from the Isl-
and of Bourbon or from Mauritius, and comparing them more carefully
with purch asi, the different stages of which I have fully detailed in my
report.

Let me say in this connection that there is. a great variability in ^mr-
chasi as to the amount of matter secreted on the scale itself, which may
very easily mislead, especially in dried specimens. In the orange proves
of Southern California the general colorational aspect of the insect is,
in all its stages, reddish-brown, the surface exudation being rarely ex-
cessive and never obliterating the reddish-brown color. This exudation
is, in fact, more noticeable upon the male larva, which, together with
his narrower, more elongate form, renders him easily distinguishable

29

from the female. In the more northern parts of the State, however, I
found that the general colorational aspect was quite different, owing to
the greater excess of the surface exudation, which frequently covers the
body in little globular masses and gives it a whitish and even greenish
aspect, and which. often rises along the middle of the body into a tufted
ridge. This form corresponds more nearly with what Signoret has de-
scribed, and it follows that this waxy surface exudation becomes denser
and still more noticeable by contraction in the dried or cabinet speci-
mens or whenever the insect has shrunken.

This question of the synonymy of the species bears directly on its
original source ; for if we have but one species of the genus, or even if
there be two, and I. purchasi is found to occur on the sugar cane in the
islands of Bourbon and Mauritius, then the presumption will be that it
originally came from these islands. In my address at Kiverside, I
called attention to the fact that this Fluted Scale seems to have become
notably injurious almost simultaneously in Australia, South Africa, and
California, and on the assumption that it infests the sugar cane on the
islands mentioned, it is much more easy to understand its introduction
to the other countries. Sugar is exported from those islands into many
parts of the world. The sugar, as it leaves those islands, is very coarse,
and all the molasses or sirup is not extracted, centrifugals not being
in use. For the purpose of draining, the sugar-makers are in the habit
of putting a piece of cane in every hogshead, and, in addition, the top
is sometimes covered with pieces of cane. In point of fact, I am in-
formed that an insect, known in the trade as the sugar-louse, is of quite
frequent occurrence in such sugar, and Professor Wiley, of the Depart-
ment of Agriculture, upon being shown specimens of Icerya purchasi
(and he is quite familiar with the so-called sugar-louse), informed me
that he thinks them identical.

On this hypothesis the initial spreading point is from some of the Pacific
islands, and the insect probably made its way first to Cape Town and
thence to Australia, New Zealand, and California. This does not pre-
clude the possibility of its importation upon other plants, but I think
it highly probable that the chief method of distribution of an insect
which is so tough as to bear long survival without food was upon sugar-
cane in sugar hogsheads, or bags, as it could be much more safely carried
in this way than upon living plants. The determination of the original
source of the pest is of vital concern in any study of its parasites, as
such would be more apt to be found in its native country than in any
countries of its introduction.

I have been quite anxious to settle definitely this question of its origi-
nal home, and have lately had some correspondence with parties in Aus-
tralia, New Zealand, and Africa. The following extracts from such
correspondence will prove of interest to the people of California. Mr.
Kirk's statement will add weight to the hypothesis that I have ventured,
while Baron von Mueller's statement also strengthens it. It may per-

30

baps be impossible at this late day to definitely settle the question of this
original source, especially as there may have been not one bnt several in-
troductions (indeed we have evidence that such was the case) into all
three of the countries in which it now occurs; but we can much easier
understand its travels if it started as a sugar-cane insect. I have itali-
cized those parts of the following letters which particularly bear on the
subject of this communication.

The sketch of the Dipteron, which Mr. Crawford found attacking
Icerya, shows a great likeness in the body to some hymenopterous En-
cyrtids ; but the wings indicate its Dipterous character and that it be-
longs to the Dolichopodid;e near Diaphorus. So far as their larval
habits are known, these flies are predaceous and live in the larva state
in the ground. Perhaps Mr. Crawford has used the term "parasitic"
synonymically with u predaceous," but I will not further anticipate what
Miss Ormerod may report.*

EXTRACTS FROM CORRESPONDENCE.

[The following are the extracts from the correspondence to which ref-
erence is made above. — Editors Press.]

Letter from Roland Trimen, of Cape Town, to Professor Riley.

As regards the evidence as to the Australian habitat originally of this insect, I re-
gret that I have nothing to add to what has been already supplied to you.

* T? IT * Tf * *

Since the commissioners report in 1877, the orauge industry of the western dis-
tricts has suffered most severely, scarce, very inferior, aud exceedingly dear fruit be-
ing now only obtainable where it used to be abundant, good, aud cheap. Where,
however, the kerosene aud alkaline solutions have been constantly applied by indi-
vidual proprietors here and there, the result (as I am informed by Mr. MacOwan, di-
rector of the botanical gardens) has been very encouraging. In the eastern districts
the effects of the Icerya's attacks do not seem to have been nearly so serious, but
whether this is due to a less suitable climate and other conditions, or to more vigi-
lance and exertion on the part of cultivators, I cannot at present determine.

* Since this was written I have received two specimens of the insect itself through
the courtesy of Miss Ormerod. These specimens are so much m utilated that it is al-
most impossible to accurately place them. The enlarged ligure seut by Mr. Craw-
ford was very misleading, the venation of the wing being wrong and also the an-
tenna?. It has no second cross vein on the wings and no sort of resemblance to the
actual anteuiue, while the two basal cells on the wings arc lacking. It Isquitelikely
that this fly belongs to a new genus. The specimens were sent to Dr. S. W. Willis-
ton, who reports that lie considers them Oscinids, but that further than t hat he could
venture no opinion as he can locate them in no genus with certainty.

Iu reference to natural enemies of the Icerya, it is of interest to note that a liitle
lady-bird. Rodolia icerya}, of which Miss Ormerod has sent me a figure, has been found
to do good work and to destroy the pesl in Australia, while news comes from Cali-
fornia that Chilocor us cacti is doing such excellent work that the trees iu some local-
ities are being entirely Greed through its instrumentality aud the lady-birds are act-
ually being sold to orange-growers at so much per ounce. C, V. R.

♦ 31

The bag spread to Natal witkiu the last few years, and last year I received speci-
mens of them, found on the common black wattle. Only yesterday I was sorry to
receive a lot -found there on the orange.

No public action in the matter has been taken since the legislative assembly, in
1887, threw out the attempted legislation on the subject. [Roland Trimen, South
African Museum, Cape Town, Cape of Good Hope, February 8, 1887.

F. S. Crawford, Adelaide, to Professor Filey.

Last year I entirely lost my colony of Icerya, owiug to the attacks of a fly. A rough
tracing of an unfinished drawing of the same I also forward. I know nothing about the
Diptera and should be obliged if you can determine the insect from the drawing. I
may say that I sent Miss E. Ormerod specimens of the fly about two months back, but,
of course, have not had time to hear what she makes of it. This is the only instance
I know, or have read of, of a true Dipteron being a Coccid parasite. [Frazier S. Craw-
ford, surveyor-general's office, Adelaide, South Australia, February 21, 1887.

Letter from Baron von Mueller, of Melbourne, to Professor Piley.

, * * * -I beg to inform you that the Icerya purchasi (or a closely allied species)
although occurring on Acacia mollissima and some congeners in the colony Victoria, has
not attacked here (so far as I can learn or had occasion to observe), destructively at-
tacked, the orange orchards. I will, however, make further inquiries as well in this
colony as in New South Wales, South Australia, New Zealand, and lei; you know the
results.

Possibly the Icerya develops more readily in a moister clime than that of Victoria, J
and thus becomes more mischievous in California than here.

The introduction of this destructive insect into your States by means of Acacia seems
to me very unlikely, because the various species of Acacias are so easily raised from seeds
that no one will think to introduce them by living plants. Moreover, it could not have been
the Acacia latifolia, which was the host of Icerya, because that species is a native only of
the north coast of Australia, and as yet nowhere existing in horticulture. Acacia armata
certainly is grown for hedges, but always raised from seed, chiefly obtained from North
Australia. It seems, therefore, more likely that when Acacias are grown anywhere,
they would afford — particularly in humid climes — a favorable opportunity for the
Icerya to spread. A similar circumstance occurred in Ceylon, and another in some
parts of Brazil, where an indigenous insect plague became aggravated, when Euca-
lyptus, on which that insect preferably seized, became reared.* Whether the Icerya
was originally an inhabitant of Victoria or merely immigrated, I will endeavor to
ascertain ; but such a subject of inquiry is surrounded with difficulty now after half
a century's existence of the colony, particularly as the Icerya drew no attention here
by any extensively injurious effects on any cultivated plants, though it may have
caused on some plants minor or transient inj ury. [ Ferdinand von Mueller, Melbourne,
Australia, March 21, 1887.

Letter from L. M. Kirk, of Wellington, New Zealand, to Professor Riley.

On returning from it protracted tour of forest inspection in the South, I find your
letter of 22d December awaiting reply. My friend Baron von Mueller is mistaken in
supposing that I have written recently on the Icerya purchasi. In a report on Fruit
Blights printed two years ago, I drew attention to the pest,*intending to treat at
greater length at an early date; but my duties as forest conservator have prevented
the intention from being carried out.

The insect is a native of the Fiji and other Pacific islands, from whence it has migrated,
probably with orange trees, to Australia, New Zealand, and California. Mr. Maskell states,

* Always from seed.

32

I believe, that it is a native of Australia, and was introduced from that country on mimosa
plants; but this is an error, and Acacias arc rarely or never introduced an living plants,
owing to their being so readily propagated from seed.

The Icerya is abundant in the northern and middle parts of the Auckland district,
and usually prefers citraceous fruits; it is, however, found in large quantities upon
some of the wattles, evincing a decided preference for the silver wattle (Acacia deal-
bata). It is, however, occasionally found on furze, manuka (Leptospermum scoparivm .
peach and apple, but on these fruits only in small quantities, and not, so far as I am
aware, doing serious damage ; in fact it is only found upon these plants when grow-
ing in the neighborhood of infested Citrads. It is occasionally found on a few native
trees, but it is not causing any great injury.

It is also found in Napier and other parts of Hawke's bay, on the eastern coast of
North Island, and in Nelson, and the northwestern corner of the South Islands. It
is also said to be found in Canterbury, but I have no direct evidence of its occurrence
in that district.

It is not found either in Taranaki or Wellington, in the North Island, except Nel-
son and possibly Canterbury.

There can be no question that it is a serious foe to citraceous fruits and to wattles.
In the vicinity of Auckland, and in many other parts of that district, it is abundant.
I have seen trees greatly injured by its ravages, but cannot say that I have seen any
killed. At present orange culture has not attained large dimensions here, but there
can be no question that Icerya is the worst foe our orange-growers will have to en-
counter.

I have not seen an Acacia killed by this pest, although the under surfaces of branches
are frequently covered. In a few established orange grounds the yield of fruit is ma-
terially diminished by the ravages of this insect.

No official documents have been published respecting the Icerya except the Fruit
Blights report already mentioned, of which a copy of a Queensland reprint is inclosed
herewith. The forest department has purchased Mr. Maskell's account of Scale In-
sects and is about to publish the same with colored plates. A copy shall be forwarded
as soon as it leaves the press. [L. M. Kirk, General Crown's Land Office, Forest and
Agricultural Branch, Wellington, New Zealand, March 25, 1887.

From an article by E. J. Dunn, in Melbourne Argus. August 1886.

I desire to call attention to a species of Coccus known as Dorthesia. This destruc-
tive pest was first observed on the island of Bourbon. Thence it spread to Mauritius, about
25 years since. In Mauritius it destroyed the orange and lemon trees, many of the orna-
mental shrubs and Acacias, and wrecked most of the beautiful plantations and shrubbtrii*
At Port Louis it still exists in loathsome masses on the handsome Talipot palm*.

About 12 years ago it was noticed for the first time in the Botanical Gardens, Cape
Town, and most probably arrived there from Mauritius with plants sent to the Bo-
tanical Gardens. During the first summer it spread about three miles into the sub-
urbs along the railway. Its fearfully destructive character now became evident, for
the orange trees, the Australian wattles, the pittosphorums, and the blackwoods be-
came loaded with this disgusting parasite, and the trees slowly but surely snoenmbed
to its attacks. * * *

All trees of theorango kind, such as lemon, citron, shaddock. &c , proved espeeially
suitable food for the Dorthesia, and once a tree became infested no amount of syring-
ing or washing prevented its destruction. The disastrous results of its arrival at the
Cape are all too evident.

Formerly in Cape Town itself, and throughout the suburbs, the orange tree lent a
charni to the gardens that no other tree could give, a'. d in the Western Province
orange-growing formed a most important source of wealth, many fanners netting sev-
eral hundreds a year from their orange groves. Some of these groves, planted by the

Huguenots and their descendants, were of great age, and, besides being profitable,
were objects of great beauty. Those of the Pearl, French Hock and Wagenmaker's
Valley were especially famous.

To-day this is all changed, and, except for a few dead stumps, these fragrant groves
and this valuable asset in the country's wealth have disappeared.

Not so the Dorthesia: it is still advancing steadily, and leaving destruction in its
wake, and will continue to do so as long as suitable food is within reach.
401— Bull. 15 3

nwwni\j[.i-MK im I i if- i.T-Ni.-i tr% r i^mr^i_i_ nnouiuuui

THE USE OF GASES AGAINST SCALE-INSECTS.

[Reprinted from Bulletin No. 71, Agricultural Experiment Statiou, University of

California.]

Some time ago the Agricultural Department was requested by Messrs.
A. B. and A. S. Chapman, Mr. L. H. Titus, and Mr. J. C. Newton, prom-
inent orange-growers of Los Angeles County, to conduct experiments
with the view of determining the efficacy of certain gases as insecticides,
with special reference to the White Scale, Icerya purcliasi. The follow-
ing is a summary of results, of which a full report will be published
hereafter :

The use of gases for this purpose has been long contemplated, and
various appliances have been suggested for the ready application of any
efficacious gas. The ease with which gas penetrates to all parts of the
tree naturally suggests its use as preferable to washes, which at best
leave many parts of the foliage and infested branches untouched, even
when sprayed with the greatest care. In order that the gas may be an
efficient insecticide it must be so poisonous that even when applied iif
small quantities it produces fatal results ; for in the application the
air confined in the tent covering the tree dilutes the gas to a great ex-
tent. Again, the gas must be capable of being generated quickly in
sufficient volume. The record below shows that only one of the gases
employed fulfilled these conditions to a satisfactory extent. Prelimi-
nary experiments with some others having shown their unfitness for the
purpose, either on account of expense or because of injury to the foli-
age, or imperfect action on the insects, their study was not pursued
further.

APPLIANCES FOR APPLICATION.

The tent for covering the tree is made of heavy bed-ticking, thor-
oughly oiled with linseed oil. This cloth serves the purpose best, as it
is very closely woven, is pliable and easily folded.

The support of the tent, devised by Mr. Titus, is a very ingeniously
contrived scaffolding mounted on wheels, which serve to move it from
one tree to another. Its dimensions are 26 feet high, with a base 20 by 20
feet. Its upper part is 20 by 12, and carries upon the top a roller made
of galvanized iron (6 inches in diameter and 12 feet long), upon which

38

36

the tent is rolled when taken from the tree. Side guy-ropes are at-
tached to the bottom. of the tent and run through pulleys at the upper
corners of the scaffold. They are used to open the tent when it is to
be dropped over the tree, and to fold it up when it is removed. The
lightness of the apparatus allows of its being easily removed by two
men, who operate the whole. If necessary, two or more tents can be
handled by the same scaffolding, one tent being left over the tree while
the scaffolding is moved to the next.

In adjusting the tent, the bottom is placed on the ground about 3
feet from the tree and covered with earth. This brings the gas to bear
upon the base of the tree and the surrounding soil.

The Generator in which the gases were produced consists of a heavy
sheet-iron cylinder, 11 inches in diameter and 13 inches high. The
bottom rests on a plank, and to the top is fitted a movable cover sus-
pended in a frame by a bench-screw. Into the cover are fitted two
pieces of gas-pipe, one for the exit of the gas toward the tent and the
other, connected with a pump, carries the gas which returns from the
tent. Two small reservoirs are also inserted in the cover ; in these are
contained the solutions which are to flow into the generator for the
production of the gas.

In order to establish circulation and to force the gas into the tent, a
pump is used which also serves to exhaust the gas from the upper part
of the tent and to force it again through the generator. It is proposed
to replace the pump bjT a small fan-blower, which is much more expe-
ditious than the common pump which was used.

t, THE GASES EXPERIMENTED "WITH.

Among the gases used were chlorine, sulphureted hydrogen, am-
monia, carbon bisulphide, carbon monoxide, carbonic acid, hydrocyanic
acid, and carbolic acid vaporized b}~ heat.

Chlorine. — Some preliminary experiments were made in small vessels
into which this gas had been introduced. Some infested branches were
allowed to remain in them for times varying from five to thirty-five
minutes without any noticeable effect being produced on the insect.
Atmospheres more strongly saturated with the gas proved fatal to the
insect in a short time. In other treatments extending over eighteen
hours, with less saturated atmospheres, only a small percentage of the
insects was killed. Ko decided effects were noticeable on the foliage
unless the gas was very concentrated.

Carbon Bisulphide. — A lime tree, 12 feet in diameter of top, was treated
with the vapor of 2J pounds of sulphide of carbon for forty-live min-
utes. At the end of this time the insects were lively, and during the
treatment had crawled up and collected around a rope surrounding the
tree at the point where the gas was being injected from the hose. It
proved that the gas thus used injures neither the insects nor the foliage.

37

It is upon record, however, that in cases where the vapor has not been
thoroughly diffused, but was allowed to flow down from an open vessel
placed in the top of the tent, serious injury was done to the foliage at
points where the undulated vapor flowed down.

Sulphureted Hydrogen. — Several treatments with this gas were made
on a small sc ale, the application lasting from five to thirty -five minutes.
The effects produced either with diluted or concentrated gas were simi-
lar to those produced by chlorine, except that even the concentrated
sulphureted hydrogen did not injuriously affect the foliage. An ex-
periment in which a whole tree was treated in the tent for forty-five
minutes with quite concentrated sulphureted hydrogen gas, showed
clearly that the effect was far from being satisfactory ; the insects for
the moment were stupefied, but in the course of an hour and a half the
majority of them were again moving about.

Ammonia. — The vapor from one pound and a half of strong ammonia
water was applied to an lL-foot lime tree for 30 minutes. The results
were disastrous to the foliage ; the leaves were all scalded, and in a few
days all dropped from the tree, and even the newer growth of wood was
injured. The insects, however, were not perceptib^ harmed.

Carbon Monoxide. — Very strong hopes have been entertained by many
for the successful application of this gas. Its apparent cheapness and
easy production, when the necessary plant is once erected, would rec-
ommend it. Unfortunately our experiments show that it is not suffi-
ciently effective to warrant its use. The gas was obtained by forcing
air through a small furnace filled with red-hot charcoal, care being taken
to cool and to measure the gas before applying it. No appreciable ef-
fect was noticeable after 40 minutes. In a duplicate experiment, in
which the charcoal was more strongly ignited and continuously intro-
duced into the barrel for 30 minutes, only slightly better results were
obtained.

Oxalic Acid. — It was thought that the production of carbon monoxide
by decomposition of oxalic acid by heat might be substituted for the
previous method of generating this gas. One-quarter of a pound of ox-
alic acid was ignited, and the gases applied in a manner similar to that
of the preceding experiment. Neither the insects nor the foliage were
harmed in the least. This experiment has incidentally shown that the
vapor of formic and oxalic acids, also produced during the heating of
the latter, is likewise ineffective ,

Carbolic Acid. — It had been suggested that carbolic acid vaporized
by heat would prove fatal to the insect. A dose of half a pound of
liquid acid was volatilized in the furnace, and the vapor blown in the
vessel containing the infected branch. At the end of 20 minutes all the
old insects were still alive, and some of the young ones, just molted,
were moving about. An hour later the foliage appeared as if scalded.

Hydrocyanic Acid. — It was only with hydrocyanic or prussic acid (gen-
erated by the action of sulphuric acid on potassium cyanide) tbat sum-

38

ciently fatal effects were secured to warrant a more thorough determina-
tion of the time of exposure and quantities of material which would
produce the best results. Numerous experiments were carried on for
this purpose, and it was shown that even small amounts were effective.
It was also shown that even in these small quantities an injurious effect
upon the foliage was produced. In the beginning of the experiments,
" mining cyanide " of potassium was used. It is a very impure material
and contains along with the cyanide a considerable amount of carbonate
of potassium. For this reason many of the first treatments were prac-
tically ineffective.

Later treatments with pure cyanide were more successful in destroy-
ing the insects, but the foliage was proportionally injured. Treatments
varying in dose from 4 to 12 ounces of cyanide, and in time from 15 to
GO minutes, showed that the effect produced on the foliage by longer
treatment was not proportionally greater than that produced by short
treatment. Neither was the effect of longer treatments proportionally
more fatal to the insects. It was thus clearly shown that the gas mixt-
ure should be of considerable strength iu order to insure rapid action.

The effect of the gas was so disastrous to the foi iage that it became
necessary to find some means of remedying this trouble. This was
sought in applying a second gas, which might preserve the foliage.
Sulphureted hydrogen was therefore injected into the tent, together
with the cyanide gas, both from the same generator; a portion of the
sulphureted hydrogen beiug introduced before the cyanide was gen-
erated. It was found that the insects appeared stupefied when the tent
was raised, but large numbers revived in a few hours. The effect of
the cyanide seemed therefore to have been decreased by the sulphu-
reted hydrogen. The foliage was nut preserved, although not so badly
affected as by treatments with cyanide alone.

Carbonic acid gas was next tried. Trees were treated with larger
doses of cyanide than heretofore used, and the carbonic acid from li
pounds of carbonate of soda was at the same time introduced with these
doses. The insects were killed and the foliage of a 12-foot tree re-
mained unharmed, while that of a 14-foot tree with the same amount of
carbonic acid was slightly injured. Thus it was shown that it would
require li pounds of bicarbonate of soda to preserve tree tops 12 feet
iu diameter, and that with tins protection the deadly cyanide could be
successfully used.

The regulation of the doses for the different sized trees so as to pro-
duce uniform treatments is calculated on the basis of the results of the
experiments which determined the amount of each constituent for a 12-
foot tree. The following table indicates the amounts for trees of differ-
ent dimensions of top, based upon the rates of cubical contents :

39

Size of tree.

Cyanide of
potassium.

Bicarbon-
ate of
soda.

Sulplmric
acid.

Feet.

Fluid ozs.

round*.

Fluid ozs.

4

• 7

. 05

.4

5

1.6

.11

.3

6

2.5

.20

1.3

7

4.0

.J9

2.1

8

6.0

.44

3.1

9

8.5

.63

4.5

10

11.5

. *7

6.2

11

15. 5

1.14

8.2

12

'JO. 0

1.50

11.6

13

25.4

1.90

13.5

14

31.6

2.50

16.6

15

39.2

2.92

20.7

16

47.5

3.55

25.2

17

57.5

4.23

30.1

18

67.7

5.05

35.8

19

70.9

5.93

42.1

'JO

90.5

6.93

49.2

In order to apply the doses easily they are prepared so that the re-
quired amounts of each ingredient can be directly measured. The cyan-
ide solution is prepared by dissolving, say, 10 pounds of the solid salt in
about 2£ gallons of water, warmed nearly to the boiling point, stirring
at intervals, cooling, and then diluting to 2J gallons. This solution
will contain about one ounce of cyanide of potassium to 2J fluid ounces
of the liquid.

The bicarbonate of soda is pulverized finely and measured off in a
vessel marked, so as to designate pounds and fractions of a pound of
the solid material. It is then placed in the generator, and the dose of
cyanide mixed with it, and, if necessary, a little water added to make
it into a thin paste. After adding the measured dose of sulphuric acid,
the puinp is worked slowly at first, and moie rapidly after the gas has
passed into the tent. The time for each treatment must be determined
by future experiments; fifteen minutes seemed to be quite sufficient
when the cyanide alone was used, but it may be desirable to extend the
treatment to thirty minutes when the foliage is protected by the car-
bonic acid gas.

It is advisable that the treatments should follow cultivation after
about four days, so that all weeds and places where the insect may find
lodgment would be destroyed. The insect will then be on, or very near,
the tree ,• the fitting of the tent to the ground is thus also much easier.

The eggs of the insect remained apparently uninjured wherever pro-
tected by the woolly covering. A second treatment, to destroy such as
may afterward hatch, will, therefore, be necessary.

It must not be understood that these experiments definitely settle the
mode of operation and the size of the doses to be used. They are merely
suggestive of a general plan which can be so perfected in the future that
the application of this remedy to other kinds of trees and insects must
be attended with good results. It simply remains for the ingenious cul-
tivator to devise the necessary appliances for its use, on a small scale,
on all sorts of fruit trees, shrubs, and plants.

nuun rvif'w njt w ixi

40

It must not be forgotten that extreme care in the handling both of
this deadly gas and of the cyanide itself is necessary. To inhale the
one or to taste or touch a wound with the other may lead to serious con-
sequences.

F. W. MOUSE.

Berkeley, June 12.