Notes on Scale Insects in Arizona

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Authors Toumey, J. W.

Publisher College of Agriculture, University of Arizona (Tucson, AZ)

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Arizona Agricultural Experiment Station.

GOVERNING BOARD, (REGENTS OF THE UNIVERSITY).

EX-OFFICIO.

HON. IvOUis C. HUGHES Governor of the TerritoryHON. F. J. NETHERTON Superintendent of Public Instruction

APPOINTED BY THE GOVERNOR OF THE TERRITORY:REV. HOWARD BIUJYTAN, A. M., Chancellor TucsonJ. G. HII^ZINGER, Secretary TucsonSEUM M. FRANKUN, Ph. B., Treasurer Tucson

STATION COUNCIL.

THEO. B. COMSTOCK, Dr. Sc. Director and Geolog-istEDWARD M. BOGGS. Irrig-ation Engineer and MeteorologistJAMES W. TOUMEY, B. S Botanist and EntomologistROBERT H. FORBES, B. S... Chemist

S. DEVOI., B. S. Agriculturist and Horticulturist

MARK WALKER Assistant Horticulturist ,R. J. FERGUSON Machinist | s t a t i o n

MARK WALKER, Jr., Acting Ass't in ChemicalLabora- f °" 'tory and Meteorological Observer, j Tucsoi*>-

JAMES L,UNSFORD, Foreman Station No. 2, PhoenixF. J. NETHERTON, Overseer, Station No. 3, Mesa CityMANUEL F. BRICHTA, Foreman Station No. 4, Willcox

The Council of the Experiment Station respectfully solicits friendly hints,criticisms and suggestions relating" to the important work they are attemptingto accomplish in the development of the agricultural resources of the Territory.

Our investigations are confined to matters affecting public interests, and noprivate engagements can be accepted by any member of the staff, except in hisprivate capacity.

Questions upon subjects within the scope of Station work will be cheerfullyanswered whenever possible.

NOTES ON SCALE INSECTS IN ARIZONA.

By J. W. TOUMEY.

SYNOPSIS.

INTRODUCTORY,

THE SAN JOSE SCALE—Aspidiotus perniciosus, Contst.Distribution of the pest in Arizona; how the insect spreads to

the trees of the same orchard or neighboring- ones; plants uponwhich the San Jose Scale will feed; description and life history;natural enemies; remedies.

DATE PALM SCALE—Parlatoria victrix, Ckll.Distribution in Arizona; rapidity with which the insect spreads;

description; remedies and natural enemies.

CALIFORNIA RED SCALE—Aspidiotus aurantii, Mask.Distribution in Arizona; description and remedies.

CALIFORNIA BLACK SCALE—Lecanium oleae, Bernard.Distribution in Arizona; description and remedies.

OSAGE ORANGE OR "FROSTED" SCALE—Lecanium pruinosum, Cog,Distribution in Arizona; description and remedies.

ROSE SCALE—Aulacaspis rosae, Bouche.Distribution in Arizona; description and remedies.

APPENDIX.

There are probably no questions in economic entomologyof greater importance than those relating to scale insects. Inwriting of these insects fifteen years ago, Dr. J. H. Comstock,then IT. S. Entomologist, said: "There is hardly any tree orshrub but that is subject to their attack; and in certain locali-ties extensive orchards have been ruined by them. Theminute size of the creatures, the difficulty of destroying them,and their wonderful reproductive powers, all combine to makethem the most formidable of the pests of our orchards andornamental grounds."

Prior to 1880 very little was done in this country towardgaining a knowledge of either the native or introduced species,or toward devising methods to eradicate them, or to lessen thegreat injury which they were causing in many widely sepa-rated portions of our country. The injurious effects of a largenumber of species became so apparent that it finally lead toan investigation, by the United States Department of Agricul-ture, of the species occurring within the United States. Sincethat time there has not been a year that our American ento-mologists have not given considerable study to these pests.Field agents from the Department of Agriculture have mademany and varied experiments in order to determine the bestmethods to pursue in destroying them and preventing theirspread from infested to non-infested orchards. Other insectswhich prey upon them have been imported from foreigncountries and liberated in infested orchards. The importationof Vedalia car din all s to feed upon the Fluted scale of Oali-

NOTES ON SCALE INSECTS. 31

fornia, was so successful that it nearly cleared that state ofone of her most destructive insect pests, and has yearlysaved thousands of dollars to her fruit growers.

Many washes have been used upon a great variety ofof scale insects and with varying success. As these insects (ex-cept for a few days during the earlier period of their existence),are protected by a covering more or less impervious to ordi-nary liquids, the effectiveness of the wash used will dependupon the following three principles:

A. Its ability to corrode the scale and reach the inspectbeneath.

B. Its ability to penetrate or soak through the scale andkill by contact.

C. Its ability to form a coating impervious to air, overthe.scale.

Any application which will accomplish any of the aboveresults will be more or less effective, it is readily seen thatin order to be most effective it is absolutely necessary that thewash comes in contact with every insect. With small trees itis possible to accomplish this, but with Urge trees it is out ofthe question. There will invariably be a few insects whichwill escape, and in a few years, with no further attention,be the source of infesting the tress as badly as ever.

Although we can never depend upon a wash to free anorchard from scale insects, especially after the trees have at-tained some size, the best washes are of great value whenfrequently and properly applied. A few scales on a tree areof little harm in themselves, but with some species when leftto multiply it is not long before the entire tree, includingtrunk, limbs, fruit and leaves are so thickly covered that thefingrr can scarcely be laid upon the tree without coming incontact with them.

By proper care and attention the careful horticulturistmay by the use of washes alone, keep his orchards compara-tively free from scale insects, but he must not think that oneapplication will be sufficient; he must know and understandthe insects which he is combating; he must keep close watchof the infested trees, and know the results of his work.

NOTES ON SCALrE INSECTS. 37

these minute pests from tree to tree and orchard to orchard.The activity of the young insect only lasts for a few days;during this period they move about over the limbs, leaves andfruit. There is no regularity to their movements, but theytravel about here and there until they find a suitable place tolocate and begin to form a scale. As soon as located the sharpbeak is thrust through the bark, the insect begins to feed, andalmost immediately a film begins to form over it, which dayby day becomes thicker and larger until the fully developedscale is the result. From the time the beak is thrust throughthe bark the insect is permanently located, incapable of chang-ing its position under any circumstances. Although greatnumbers of the young scales locate upon the leaves, it is mostlythose which fix themselves to the branches that live throughthe winter and reproduce the following spring. The leavesfalling to the ground wither and dry, the supply of food failsand as a result the insect being incapable of movement dies.

PLAiNTS UPON WHrCH THE SAN JOSE SCALE WILL FEED.

Although this insect is primarily an enemy to pear cul-ture there is but little doubt that nearly all species of Rosa-ceous plants will support it. Tt has been found to some ex-tent upon species belonging to other families. In Salt RiverValley it is almost entirely confined to pear and apple trees.In the observations made very few peach trees were found in ascaly condition and none of those found were badly infested.Although the peach will support the Ban Jose scale, it does notincrease and spread with the same rapidity as on the pear andapple. Apricot orchards by the side of badly infested pearorchards were almost or quite free from scales. A row of quincetrees at one side of a scaly orchard was not infested in theleast so far as we were able to discern. The various varietiesof pear and apple evidently offer but little protection againstthe San Jose scale. When once established it seems to thriveand increase almost equally as well upon all varieties of pear;the apple, however, is not quite so favorable to its development.

Dr. John B. Smith* in a recent bulletin on this insect re-

*Bulletin No. 106, New Jersey Agricultural Colleg-e Experiment Station.

38 BULLETIN No. 14.

ports it infesting the currant, gooseberry, rose bushes, a E uro-pean elm, and a few specimens of what were taken to be thisscale, were found by him on an English walnut. The fact thatthis insect feeds upon such a great variety of plants, and thatunder favorable conditions it multiplies upon one variety al-most as well as upon another make it an exceedingly fomid-able pest, which requires considerable thought and energy onthe part of the orchardist to keep in check,

DESCRIPTION AND LIFE HISTORY.

Although the more important facts in regard to the lifehistory of this insect have been known for a number of years5

when knowledge was had of its introduction to eastern points,a more thorough and comprehensive study was undertaken bythe Division of Entomology of the United States Departmentof Agriculture. The life history as here given is essentially aspublished by the Division of Entomology in a recent fcircularand in a more recent article in ^Insect Life, supplemented byobservations made in Arizona during the past winter andspring. The electrotypes used in the illustrations herewith,were kindly procured through the courtesy of the Chief of theDivision of Entomology.

The San Jose scale is one of a number of related insectswhich infest the fruit trees and native plants of the south-west, and which has lately been found as far east as theAtlantic coast. It is flat, but slightly raised aboye the surfaceof the bark and usually closely resembles the bark of the twigsin color, varying in diameter from nearly one-eighth to one-sixteenth of an inch. When crowded on the branch it is con-siderably smaller than where isolated. The males are aboutthe size of the smallest females. Where isolated the scales areperfectly round but when crowded they are usually slightlyelongated or irregular and may overlap each other. A moreor less conspicuous elevation rises from the center of each scaleas a slightly elongated point, which varies in color from blackto yellowish.

tCircular No. 3, Second Series, U. S. Department of Agriculture, Division ofEntomology.

IVol. VII, No. 4, p. 283.

NOTES ON SCALE INSECTS. 39

If a badly infested limb be scraped, many scales arecrushed and a yellowish, oily liquid appears. This liquid isthe indication of healthy, living insects and comes from thesoft yellow insects beneath the scales. On removing the scalesit is usually observed that the bark is not of the same color ason healthy twigs but is of a more or less distinctive purple,which sometimes extends to the wood. It might be statedhere, that scaly fruit is conspicuous in that a purple discolora-tion surrounds the edge of each scale. The older scales aregrayish white while the younger ones vary in color from whiteto nearly black. Asa rule the great patches of grayish scaleson tree-trunks and large branches are the vacant houses ofscales long since dead. The active insects are more apt to beon the twigs, leaves and fruit, where the epidermis is moretender and consequently easier to penetrate. During thewinter and mid-summer they are mostly mature or in a nearlymatured condition. Young insects were found last year asearly *as March. In southern Arizona by far the greaternumber of mature insects are found in the spring and fall.At almost any time during these seasons the larvae may be ob-served crawling over infested trees. During July and August,two of the warmest months in the year, the young are rarelyfound in great numbers, and the more mature scales appearalmost as dormant as in mid-winter.

This insect is viviparous, that is, gives birth to livingyoung, resembling in this respect our common plant lice. Theyoung are very small but extremely active, and as soon asborn they leave the parent scale and spread out over the twigs,leaves and fruit. After traveling about for several hours theysettle down and each begins to form a scale. In from three tofour weeks the mature males begin to appear and in about fiveweeks from time of birth the females are mature and begin togive birth to young. There is a marked difference between themale and female The full grown male is an active insectwith small membraneous wings, while the full grown femalehas neither legs nor wings, and has but little resemblance to aliving insect, but may be likened in appearance to a small flatseed.

The females continue to reproduce for two months, or even

40 BULLETIN No. 14.

longer, so that two or three generations may be living on theplant at the same time. The rapidity with which one genera-tion follows another, accounts for the rapid increase, underfavorable conditions, when the pest has once been introduced.

NATURAL ENEMIES.

This insect has but few parasites, and it is very doubtfulif, in any case, they can be depended upon to keep it in check.Last spring I observed a lady-bird feeding on the young scalesin Salt River Valley. At this time many old scales werefound punctured with minute holes, likely the exit of somesmall hymenopterous insect, probably Aphelinus fuscipennis,which has been bred from this scale in California.

REMEDIES.

The difficulty of effectively treating these insects, protect-ed as they are by a thick scaly covering, impervious to mostliquids, is apparent to all. Whale-oil soap, potash, lye, kero-sene emulsion, resin, sulphur, lime and salt, have been vari-ously compounded and used in varying degrees of strength incombating them. As a rule, the effectiveness of the applica-tion depends upon the strength of materials used and thethoroughness with which they are applied. Some of theabove materials, depending upon the formula used, are mixedwith water and a thorough application made by means of asuitable force pump. All ordinary trees will stand the appli-cation of a strong wash much better in winter than in sum-mer; consequently many washes which prove destructive insummer, may be applied two to five times as strong in winter,with little or no injury. It is evident then that the winterseason is the best time to undertake the destruction of this, aswell as other scale insects.

A number of orchardists are in the habit of giving theirtrees, each winter, a thorough washing with a solution ofpotash or whitewash. This can be recommended as an ex-cellent practice, whether or not the trees be infested withscales. There is no doubt but in a number of instances, thisscale has been held in check by these applications. In thematter of remedies I quote the following from the circular

NOTES ON SCAIvB INSECTS. 41

issued by the Department of Agriculture which I have alreadyreferred to:

INSECTICIDES.

"Where trees are found to have become badly infested thesafest and, in the long run, the most economical course willbe to cut them down and burn them, trunk and branch.Where the infestation is less marked, insecticide washes andsprays may be used. The young lice, before they have begunto secrete scales (and at this time they can only be discoveredwith the help of a magnifying glass), may be destroyed byspraying with kerosene-soap emulsion. A formula for thismixture follows:

Kerosene gallons... 2 —67 per cent.Common soap or whale-oil soap pound...% ) ^^ „„„ __„ +Water .... ..gallons... 1 f=-« percent.

Heat the solution of soap and add it boiling hot to thekerosene; churn the mixture by means of a force pump andspray nozzle for five or ten minutes. The emulsion, if perfect,forms a cream which thickens upon cooling, and should ad-here without oiliness to the surface of glass. If the waterfrom the soil is hard, or has a large percentage of lime, add alittle lye or bicarbonate of soda, or else use rain water. Foruse against scale insects dilute one part of the emulsion withnine parts of cold water.

For the older scales, the washes may be divided intothose which can be used in summer without damage to thetrees, and those which are so strong that they can only be ap-plied during the winter season when the tree is dormant.None of the summer washes are perfectly efficacious, and it isdoubtful whether any of them will prove of more benefit thanthe kerosene emulsion just mentioned. Owing to the fact thatwe have had no summer experience with this insect in theeast, we can not state positively the strengths of certain washeswhich may be used successfully without damage to the treesduring summer. In California, however, one of our agents,Mr. D. W. Coquillet, has used with success during the sum-mer a resin wash which was made in following proportions:

Resin pounds... 20Caustic soda (70 per cent, strength) do 5Fish oil pints 3Water sufficient to make .gallons... 100

It is probable that this mixture will not be too strong for

42 BULLETIN No. 14.

eastern trees, since, in general, with other insecticides, theclimate of California seems to render trees rather more sus-ceptible to injury than is the case in the east. For a winterwash the same ingredients may be used in the following pro-portions:

Resin pounds... 30Caustic soda (70 per cent, strength)., do 9Fish oil pints \x/2Water sufficient to make gallons... 100

The most favored winter remedy in California, however,is the lime, salt and sulphur mixture. This is generally usedthroughout the state by progressive fruit-growers. It consistsof—

Unslacked lime pounds 10Sulphur pounds 5Stock Salt pounds 4Water to make gallons 15

This wash will do great damage to the trees if appliedduring the growing season, and should be used only in winter.All the sulphur and half the lime are placed in a kettle, and8J gallons water added, after which the contents of the kettleare boiled briskly for about an hour. The solution, which atfirst is yellow from the sulphur, will turn very dark brown,assuming more or less of a reddish tint, and will finallychange from a thick batter to a thoroughly liquid condition,the product being ordinary sulphide of lime. All the sulphuris added to the remaining five pounds of lime and the latterslaked, after which the slaked lime and salt are added to thesulphide of lime already obtained, the whole being then di-luted with water to make 15 gallons. This should be strainedbefore application, as it does not form a perfect liquid solution,on account of the considerable quantity of undissolved lime,which will soon settle to the bottom unless the solution is con-stantly stirred while being sprayed.

In the experience of the Division in California andWashington this solution has not been as successful as couldbe desired, but it has considerable popularity among the fruit-growers of California.

INSECTICIDE APPARATUS.

For the making of emulsions and the application of in-secticides a good force pump is essential. The best apparatusfor the making of an emulsion is one of the small hand pumps

NOTES ON SCALE INSECTS. 43

known as hydronets or aquapults, which are manufactured byall pump-makers, the Johnson type being preferable. For theapplication of sprays to trees either the knapsack pumps forsmall trees and young orchards and nursery stock, or thelarger cart or barrel pumps, will be desirable. The aquapultor hydronet can be obtained for about $9 and the knapsackpumps for about $15. The larger barrel and tank pumps,when arranged ready for use, range in price from $25 to $75,depending on the size and complexity of the machinery,

A very satisfactory apparatus can be made at much lesscost by buying a good force pump at a cost of $9 to $12, andfixing it to a strong barrel or wooden tank. All the pumpmanufacturers have pumps that are adapted to this purpose,and the cost of the apparatus by this means will be limitedpractically to the cost of the pumps, nozzles, and hose, whichshould not exceed at the outside $15.

The nozzle in most general use is of the Cyclone type, andis ordinarily styled on the market the Vermorel nozzle. Thiswill prove very satisfactory, particularly for smaller trees, andis the one commonly supplied with the knapsack sprayers.The Nixon nozzle, which is supplied only with the Nixonpumps, is a very serviceable one, and particularly advantage-ous for use with large trees.

THE GAS TREATMENT.

This method has not been extensively used in Californiaagainst this insect, but has been used with very considerablesuccess against the so-called Red Scale upon orange and lemontrees. It is an expensive operation, but is unquestionablymore thorough than spraying. Trees infested with differentkinds of Aspidiotus have been entirely freed by a single appli-cation of this gas.

The treatment consists in enveloping the tree in an air-tight tent and afterwards filling the tent with hydrocyanicacid gas, generated from fused potassium cyanide, sulphuricacid, and water. This gas is much lighter than air and assoon as generated rapidly rises and fills the tent. It is ofcourse fatal to all forms of animal life, and care must be exer-cised in using this treatment. The tent is usually construct-

NOTES ON SCAIvE INSECTS. 45

itself and of the hydrocyanic acid gas must be strongly im-pressed upon those who undertake to use this treatment forthe first time. The cyanide must be kept where children andanimals can not get at it; it must be kept in tightly closedvessels, and must be plainly labeled "Poison." During theprocess of treatment every care must be taken to preventhuman beings or domestic animals from inhaling the gas."

Whale-oil soap, resin, sulphur and lime washes have beenused in combating this insect in Arizona. We have not asyet undertaken the gas treatment, but have depended uponwashes as herein given to hold the pest in check. The sum-mer washes, if applied but once or twice during the season,are comparatively of little value, as they can only be relied onto kill the young insects which have not begun to secrete theirscaly coverings. As the San Jose scale is found in all stagesof growth during almost every month in the year, we canreadily see the futility of one or two applications of any of thesummer washes. A strong winter wash which will kill all thescales with which it comes in contact, is to be preferred. Aspreviously stated, although these winter washes are very valu-able, there is no application which can be depended upon toentirely free a badly infested tree from this pest. In therecent experiments in the east, conducted by Mr. Coquillett,even the gas treatment failed to destroy all the eggs, wherethe scales were thickly crowded on the branches. In a recentarticle in Insect Life, Mr. Howard summarized a long list ofexperiments made during last November and December, asfollows:

1. Three pounds dissolved in one gallon of water. Fatal toall the scales on the trees sprayed with it.

2. Two pounds in one gallon of water. Same result.3. One and one-half pounds in one gallon water. Fatal to

ninety per ceat. of the scales.4. One pound in one gallon of water. Fatal to eighty per

cent, of the scales.5. One-half pound in one gallon of water. Fatal to one-half

the scales,RESIN WASH.

6. Six times summer strength. Resin, 120 pounds; causticsoda, 30 pounds; fish-oil, 15 pints; water sufficient to make 100gallons. Fatal to all the scales on the trees sprayed with it.

7. Four times summer strength. Resin, 80 pounds; caustic

HOTELS ON SCAI^E INSECTS. 47

influenced by rains for a considerable time after the applicationswere made.

From the above will be seen the great value of commer-cial whale-oil soap against this insect. I have found it equallyas effective against the Date-palm scale (Parlatoria victrix),infesting date-palms growing at the Phoenix station, andagainst the Cactus scale (Diaspis cacti) infesting cacti growingat the University.

A popular treatment, one which I have seen practiced tosome extent in Arizona, but which I would recommend onlyfor badly infested trees, is to give the trees a severe pruningand with a stiff brush or broom go thoroughly over the trunkand branches applying the strong resin or whale-oil wash.This treatment should be made before the buds start in thespring. In conclusion I quote the following from Mr. Howard,chief of the Division of Entomology, United States Depart-ment of Agriculture:

"No orchardist should admit a single young fruit tree, ora single cutting, or a single bud, from a distance into hisorchard, without first carefully examining it and satisfying him-self absolutely that it does not carry a single specimen of theSan Jose Scale. If this plan is adopted by every one inter-ested, and without exception, the rate of spread of the speciescan be limited to the natural spread by crawling, by winds,and by the aid of other insects and birds.

We wish particularly to impress upon the minds of fruitgrowers that as soon as this insect is found to occur in anorchard the most strenuous measures must be taken to stampit out. No halfway measures will suffice. The individualmust remember that not only are his own interests vitally atstake, but those of the entire community in which he resides.Trees badly infested should be instantly burned, as previouslystated. The individual may think that he can not bear theloss, but the loss in consequence of the slightest neglect will bemuch greater. The fact, too, that there is a community ofinterests among fruit-growers in this matter must not be lostsight of. Fruit-growers must be mutually helpful in an emer-gency like this.7'

48 BUI,IvETlN No. 14.

DATE PALM SCALE.Parlatoria victrix—Ckll.

Order, Hemipteri. Family, Coccidcz,This scale was brought to Arizona on date palms, imported

from Africa and distributed by the Department of Agriculture,some four years ago. At the time the palms were distributedthey were known to have been infested, * but as they had beensubjected to careful treatment it was supposed that the scaleswere all eradicated. At the time of distribution the specieswas considered 4o be Parlatoria zizyphus (zizyphi of some auth-ors), but I have been recently informed by Professor D. T. A.Cockerell, to whom 1 sent specimens for examination, that itis a new species which he has recently described under thename Parlatoria victrix. The fact that these insects have sur-vived the thorough treatment that they were subjected to byMessrs. Townsend and Marlatt, before the palms were dis-tributed, strongly supports the opinion that infested stock,imported into a new country, should be destroyed. The halfdozen palms received at this Station were set out on theStation farm at Phoenix, and of this number, two years ago,two plants were found to be badly infested.

It was impossible for me at the time to personally attemptto eradicate the pest, and the experiments were conductedunder my direction, by Mr. M. Moss, who was at that time incharge of the Phoenix Station.

A strong kerosene emulsion was first tried in this work.One part of emulsion to five parts of water was first used, butat this strength a large percentage of the scales survived. Thenext week the emulsion was tried diluted with only one partof water. Branches from the sprayed trees were sent me forexamination and after a careful inspection I failed to findmore than three to five per cent of the scales alive, and con-cluded that another spraying would completely eradicate them.It was directed that the trees be again sprayed, but after thisspraying, material was not received for examination. InApril of the present year, while at the Phoenix station, it wasfound that a sufficient number had withstood the treatment of

*See Insect Life, Vol. I l l , pp. 441, 443.

NOTES ON SCALE INSECTS. 49

the previous year to restock the plants. They were not, how-ever,nearly as badly infested; the scales being confined to the twooriginal plants and several suckers, that had been removedfrom these plants and planted elsewhere. The two badly in-fested plants were ordered to be removed, and the small plants,which had been taken as suckers from the infested ones, werethoroughly sprayed with a solution of whale-oil soap. Thissolution was used at a strength of one and one-half pounds ofsoap to one gallon of water, and after a careful examinationnone of the insects were found alive.

DESCRIPTION.

This scale, although small, is conspicuous against thedark green leaves of the date palm. They infest both sides ofthe leaves, frequently occurring in such numbers that theyover lap each other so as to almost completely hide the surfaceof the leaves. In general appearance, they represent a darkscurfy deposit. The female scales are oblong, nearly black,with a white margin. They are very flat and adhere closelyto the smooth leaves. The scales of the males are linear,white, and less than one-fourth the size of the female scales.As with the San Jose scale in this Territory, the young arefound during nearly every month of the year, hence they arealmost equally difficult to eradicate.

RAPIDITY WITH WHICH THE INSECT SPREADS.

It is evident from the observations made, that the spreadof thip insect from infested to non-infested plants, even whenonly a few rods apart, is a very slow process. In the threeyears that the plants under consideration have been infested,none of the scales, so far as we were able to discern, after anextended examination, have spread to neighboring plants,only a few rods distant. There is a probability, however, thatat any time, birds and insects flying between these plants, willcarry the young insects with them. When plants are grownclose together, as in a nursery, or where suckers are takenfrom an old plant, the probability of being infested is muchgreater; as this scale spreads with great rapidity over portionsof the same plant, or neighboring plants when in contact.

50 BULLETIN No. 14.

The young lice crawl rapidly and sometimes move considera-able distances, before settling down to secrete their coverings.

REMEDIES.

The Date Palm scale should be treated much thesame as the San Jose scale. The strong kerosene emul-sion and the solution of whale-oil soap were bothsuccessful in greatly reducing their numbers. Thelatter proved in our experiments to be the mosteffective, in fact, practically freeing the plants of theinsects. The lime and resin washes were not tried, but it ismore than likely that they will be found more or less effective.The foliage of the date palm is thick and rigid, and will notbe injured by the application of a strong wash, even in thegrowing season.

A lady-bird (Coccinella abdominalis), was found in con-siderable numbers, feeding on this scale, at the PhoenixStation.

OTHER SCALE INSECTS OF ECONOMIC IMPORTANCEFOUND IN ARIZONA ON CULTIVATED PLANTS.

The following Coccids have been found in Arizona onlyon a few plants, and in no case in sufficient numbers to causemuch injury. The great harm which they have caused insome parts of the country, more especially in California, issufficient excuse for the following brief remarks in regard tothem. Their numbers in this Territory have been so limited,and the injury caused so little, no remedies of any naturehave as yet been used against them.

CALIFORNIA RED SCALE.Aspidiotus aurantii, Mask.

This Scale, so well known to the citrus fruit growers ofthe Pacific Coast, where it was introduced some years ago onlemon trees imported from Australia, first found its way intoArizona about two years ago, on a few specimens of Komquat{Citrus Japonica), brought to the Experiment Station at Tuc-son from a California nursery. These plants were badly in-

NOTES ON SCALE INSECTS. 51

fested with the red scale the next year after being broughthere There is no danger, however, that it will be harmful,in this locality, to other than the few plants on which it wasintroduced, as it is only known to infest citrus fruits. It is,nevertheless, a dangerous pest, and if it should be introducedin a similar way, into any of the citrus regions of Arizona, itwould without doubt, become very destructive to citrus fruitculture in this Territory. In California it is among the worst,if not the very worst, of all the insects infesting citrus fruitsIf once established in the orange groves of Arizona, there isno reason why it would not become equally as destructivehere. This insect is found on all parts of the tree; the trunk,limbs, leaves and fruit, being alike infested.

DESCRIPTION.

The female scales are small, with a nipple-like promi-nence at or near the center. The scale is thin and somewhattranslucent, so that the small insect beneath is readily ob-served. That portion of the scale under which the insectrests is much darker than the border. The dark portion iscurved, "U" shaped, corresponding to the form of the insectbeneath. The color varies from dull yellow to reddish brown.The male scales differ from those of the female in that theyare only one-fourth as large. The gas treatment is the mostpopular remedy against this scale, and is used extensively incombating it in the orange groves of California.

CALIFORNIA BLACK SCALE.(Lecanium oleae, Bernard.)

This insect has been sent to the Station at Tucson, severaltimes within the past three years, from Salt River Valley.In each caee it was taken from young orange trees, purchasedfrom California nurserymen, or from local dealers handlingCalifornia trees. Specimens were sent for identification, onlya few weeks ago, by a gentleman living in the vicinity ofPhoenix, who wrote that the scales sent were from youngorange tree*, purchased only a few months before, from a localdealer who handles stock from one of the nurseries of southernCalifornia. In my reply I emphasised the care to be taken

52 BULLETIN No. 14.

in purchasing young trees, whether from California or fromlocal nurserymen, and see to it that they are free from scaleinsects. My letter was sent to the dealer of whom the treeswere purchased, and in a recent communication from him heinforms me that he has observed this scale for some years onstock imported from California, but that he has never as yetknown an instance where it has not been killed by the heatand dryness of our summer months. Personally, I have notbeen in a region where I could observe whether this scale willsurvive the heat and dryness of our summer months. Its de-velopment is very slow, there being but one or two broods ayear, and it is more than likely that the climate of Arizona ismore disastrous to its development, than in the case of eitherthe San Jose scale or the Date Palm scale.

DFSCRIPTION.

The adult female scales vary in color from dark brown tonearly black. They average nearly one fifth of an inch inlength, are about one-half as high, and are a little longer thanbroad. Along the back, is a prominent longitudinal ridgeand two less prominent transverse ones, which divide thescale into three nearly equal portions. It is a large, dark,conspicuous scale, not readily mistaken for other species foundin Arizona. Five or six months intervenes from tjie time ofhatching before the scale begins to show the characteristicridges. Nearly all the specimens that have been receivedfrom Salt River Valley, show the puncture of some parasite,but in all specimens examined the parasites had escaped.This scale has quite a number of insect enemies; from this andfrom the fact of its slow development it is not likely to becomevery injurious in Arizona, at least, for some years to come.So far as known, it has been found in this Territory only onthe orange and oleander. It infests, however, all kinds ofcitrus fruits and a great variety of other fruits, includingapricot, pear, plum and olive.

REMEDIES.

Kerosene emulsion or whale-oil soap, used as strong asthe infested plants will bear, will be found effective in treatingthis scale.

NOTES ON SCALE INSECTS. 53

OSAGE ORANGE, OR "FROSTED" SCALE.

(Lecanium pruinosum, Coq.)

I first found specimens of this scale some two years ago,infesting hedges of osage orange, growing in Salt River Val-ley. So far as known from my own observations, and fromcorrespondence, it is found in Arizona only on this plant;Mr. Coquillett, in his destription of this insect, * states thathe has found it in California, infesting ash, apricot, prune,peach, cherry, pear, apple, English walnut, birch and severalother plants. It has also been reported as infesting grapevines.

DESCRIPTION.

Of the scales noted in this Bulletin, this species most re-sembles the Black scale, and like the Black scale it is ratherslow in development, and not likely to become a serious pest inArizona. The adult female scales are light brown, sometimestinted with red; thinly covered with alight powdery substance;usually a little larger than the Black scale and without theprominent carinate ridges, so conspicuous in the latter species.The surface of the scale is usually very uneven. On theold and dried scales, as pointed out by Mr. Coquillett, thepowdery substance becomes almost entirely removed and thesurface, rougher, especially along the back.

REMEDIES

In Mr. Coquillett's investigation of this scale in southernCalifornia, the following wash was used and proved fatal toall the scales, besides destroying the greater number of theeggs: Resin, 30 pounds; caustic soda (70 per cent) 9 pounds;fish oil, A\ pints; and water to make 100 gallons. This washshould be applied only during the dormant season, as it isliable to cause injury to the trees if applied in summer.

The washes proposed against the Black scale will, mostlikely, be equally effective in combating this insect.

*Insect Life, Vol. I l l pp. 382-384.

54 BULLETIN No. 14.

ROSE SCALE.

Aulacaspis rosae, Douche.

This is a widely distributed species, found throughoutthis country and Europe. It usually infests the bark of rosebushes but has been found, to some extent, on species ofblackberries and raspberries. It has been sent me severaltimes from the vicinity of Phoenix and Tempe, where in eachcase, it was found on rose bushes.

DESCRIPTION.

The female scales are nearly circular, and almost snowywhite, with a slightly raised yellowish point (the exuviae) alittle to one side of the center. They are rather small, beingfrom one-eighth to one-tenth of an inch in diameter, but theirwhite color, against the deep green epidermis of the plant,makes them, especially where crowded, very conspicuous. Themale scales are considerably smaller than the female scales;are the same color, but instead of being circular, are long andnarrow, with the larval skin crowded to one end.

This scale has a number of parasites, but the only one Ihave observed in Arizona, is the "golden chaicid" (Aphelinusdiaspidis, How.)

REMEDIES.

In using washes against this scale, it should be remem-bered that rose bushes will be injured by the application of astrong wash. The best remedy, will be to spray thoroughlyand frequently, with a dilute kerosene emulsion, one part ofstandard emulsion to ten of water.

NOTES ON SCAI^E INSECTS, 55

APPENDIX.It is thoug-ht desirable to append to the matter presented in this

Bulletin, relating" to the scale insects of economic importance, a listof the non-economic species indig-enous to the Territory. No pre-tension is made that this is a complete list, as it only represents thespecies that I have collected in the past two years, incidental toother work. A number of them are new, and it is possible thatsome of them, later, may be found to infest cultivated plants. Thedescriptions are brief, only enough descriptive matter being" givento enable one to identify them. Acknowledg-ments are due Pro-fessor Cockerell, a specialist in this group of insects, for his kind-ness in identifying- the species unknown to me, and describing- thenew forms.

Lecanium phoradendri, Ckll.—Female scale, dark brown toaltnost black, circular in outline, flattened, shiny, moderately con-vex, wrinkled, and pitted; immature specimens, greenish. Thediameter of the scale about 2>l/2 mm., height, 1 mm. Derm granu-lose; anal plates broad; antennae moderately long-, seven-jointed.Male scale, shiny, 5 mm. long-, 1 mm. broad.

Found throug-hout southern Arizona on mistletoe {PhoradendronJlavescens), frequently occurring* in such numbers as to destroy theplant. When badly infested the foliag-e turns yellow, and finallywithers and dies. It infests both leaves and stems.

Coccus cacti, sub. sp. confusus, Ckll.—This Coccid is closelyrelated to the cochenille insect {Coccus cacti) of Mexico. The adultfemale is dark reddish-brown, about 6 mm. long-, and three-fourthsas wide. It is covered with a dense mass of white cottony substancewhich completely hides the insect. When the plants are badly in-fested, large patches, two or more inches in diameter, are coveredwith this cottony material, which is conspicuous ag-ainst the greenstems of the cactus. On removing- the white substance, the insectis seen to be rather strongly seg-mented. The mature male is some-what lig-hter in color and is provided with wing-s.

This insect is frequent throug-hout southern Arizona, infesting-various species of cacti. During- the past year I have found it onOpuntia arborescens, O. versicolor, O. fulg-ida, O. Eng-elmanni, andO. pheacentha. It is readily recog-nized by its conspicuous cottonycovering, and by the characteristic cochenille color observed whenthe insect is crushed.

Tachardia larreae, Comst.—This insect is related to the in-sect which produces the gatm-lac imported from India. The lacis brig-ht reddish-brown, semi-transparent; appearing-in more or lessg-lobular masses, or, when crowded, as a continuous incrustation,from 4-6 mm. thick, completely surrounding- the stem. The body ofthe female is nearly g-lobular in outline, with prominent lac tubes,and anal tubercle. It infests the creosote bush * {Larrea tridentata)which is the most abundant shrub on the South-western plains.The lac produced by it is nearly as valuable as the im-ported lac, but on account of the small quantity found on a singleplant, it probably will never be of commercial importance. Thelac produced by the closely related species, Tachardia fulgens, de-scribed below, is extensively used by the Mexicans as a remedy forlung- and stomach troubles, and is kept for sale in many of thedrug--shops throughout the Southwest.

Diaspis cacti, Comst.—Female scale nearly circular, moder-

* This bush is known in southern Arizona as "grease-wood;" the name "creo-sote-bush," is seldom, if ever, applied to it.

56 BULLETIN No. 14.

ately convex, about 1% mm. in diameter, white, with a thin border;a slightly raised yellowish brown point (the exuviae,) a little to onesiae of the center. The male scales are white, and much smaller,about 1 mm. in length, and one-third as wide.

This scale infests various species of cacti throughoutsouthern Arizona, including Opuntia fulgida, O. arborescens, O.versi color, and Cereus enneacanthus.

Prosopophora prosopidio, Maskell.—-A species with 8-jointedantennae, recently described in Trans. New Zealand Inst., frommaterial collected in Arizona, on Mesquite.

NEW SCALE-INSECTS FROM ARIZONA.

BY T. D. A. COCKEREIvIv, NEW MEXICO AGR. EXP. STA.

The following new species, received from Prof. Tourney, havenot been published at the time of writing. Although it is proposedto give full details concerning them elsewhere, it seems desirable topresent, in this connection, just as much descriptive matter as maybe necessary for their identification.

1. Diaspis toumeyi, n. sp.—Female scale circular or nearly so,moderately convex, about 2 mm. diameter, white tinged with yel-lowish or brown; exuviae sublateral, first skin exposed, pale strawcolor; second skin, exposed by rubbing, orange. Median lobes offemale very large, oblique, strongly divergent, finely crenate, caud-olateral group of glands with 25 orifices, cephalo lateral 36, median24. Male scale obscurely unicarinate. On Holacantha Emoryi, nearMaricopa.

2. Parlatoria victrix, n. sp.—Female scale much resemblesP. zizyphus (which is not rarely found on lemons), but the largesecond skin, instead of being all black is broadly margined withpale straw color. The microscopical characters of the females arealso different. At Phoenix on date palrn imported from Egypt.

3. Lecanium mirabile, n. sp.—Female subglobose, dark grayishbrown, with numerous white rings, the dark centers of which aredepressed and shining. The diameter of one of these rings is about1 mm., but some are larger, some smaller. The length of the insectis about 7 mm. Derm microscopically tessellate. Antennoe veryshort, 6-jointed, last joint, button like. Embryonic larva with twoimmense bristles on each side. On mesquite, Tucson. Forms thetype of a new subgenus, or genus, which I call Toumeyella.

4. Ceroplastodes acacicz, n. sp.—Scale snow white, more no-dulose than C. niveus, but less so than C. dalece. Antennoe8-jointed. Male scale elongate, white, nodulose, with a marginalfringe of small nodules. On Acacia constricta, Tucson.

5. Tachardia pustulata, n. sp.—The only crimson lac hithertofound in the United States. The scales are about the color ofblack-currant jelly, about 3 mm. lon;^, rounded, with small pustule-like prominences. Young individuals present a dorsal horn like theadult of T. cornuta. Lac tubes broadening to base. Spine with abroad more or less triangular base. Near Phoenix, on an unknowncomposite.

6. Tachardia fulgens, n. sp.—An orange lac, very brilliant incolor, a sort of deep apricot color. Scales massed together, more orless surrounding twig. Single scales about 4 mm. long with astrong blunt dorsal prominence, and a prominence at one end, all soplaced that when the scales are viewed sideways they often presenta ludicrous resemblance to a hnman face. Spine stout. Lac tubescylindrical. Neighborhood of Tucson, probably on Sesbania.