ATE PLANT BOARD
K'[ ", "' ". .
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May 1943 E-595
United States Department of Agriculture
J Agricultural Resea&rch Administration
Bureau of Entomology and Plant Quarantine
PALIATORIA CHI!'TN!SIS MIPLATT l/
'V By Ho-ward BQaker and Nathan Stahler, Divis io, of Friait IBsect
Investigations, and A. C. Johnson, Division of Control Inves-
Stigations, Bureau of Entomology and Plant Quarontina, Ari-
v'l cultural Research Adninistratior, and Lloyd Adams and R. C.
:" iroescsmer, Missouri State Departrent o:f Agriculture
Specimens of a scale insect found in St. Louis, ,!o., in A-)ril 1940 by
:i:. an entomologist of the Missouri State fepartent of Lriculture were suobse-
Squentl.y determined by the aBureau of Entomology and Plant QZurantine of the
United States Department of Agriculture as P-rlatoria chinensis Marlatt, a
scale insect not heretofore reported as occurring in the United States. A
: preliminary survey conducted by the Missouri State Department of Agriculture
Ht ring the spring and summer of 1940 revealed that t':is insect wa 1 well estab-
I listed on such plants as althea, privet, lilac, buckthorn, red chokeberry,
S nd purpleleaf plum in the Missouri Botanical Garden and Tower Grove Park,
^ and on other properties radiating therefrom for a distance of several blocks.
T his scale insect has been reported in Ja-nrn, China, Egypt, a.ndO
.. India and has been intercepted by inspectors of the United States Department
S of Agriculture on plants from Japan, China, and India, Despite all efforts
,,, that have been made to trace the origin of the infestation of Parlatoria
S chinensis in St. Louis, the tire and method of its introduction are urniowm.
I/ This circular superscdes E-535, Parlatoria chinensis Mcx.rlatt,
A Scale Insect Recently Discovred in the United States, which was
issued in April 1941. Information given in circular 3-535 has been
utilized. freely in this revision,
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A. ',l i 'J-j ...-.. 'I: m ,' -"* i
Little infor.-ation is avail-abl-.: in the litwraturo with regard to t1ho :
s:-asonal history, habits, or status of Parlatoria chinensis as a pest:.- Other.-. ;
3p<,cies of Parlavoria are serious vnsts in this and other countries,' however, v,
and tho,- host list of this c-vcios, as recorded in available records and litCera
tur.-, is suich as to indicate thi.at it could become an important pest of many '^
of our d.e.ci.uous frtit trees, sha-3 troops, and shrubs. :
Th. following plants havZ been mentioned as hosts of this insect in:,,:;
foroignt comuitrijs and from nlant importations: '
3nahii.;ria (mountain-sbonv, orchid tree) .:
Cassia fistula (pudding-pipe tree, golden-shower) i
Ficiz (fig, etc.) ":* ':
Hibiscr.s (rosernallow) 3. N:
Juglans (uralaut) :[
Justicia alba "
Malus (crab apple only) .' '
ITorium (oleander) *'
Olca (olive) "
PrLu.s (-plun only) A .
PNras (flowering variotios of pear only) '',:i
Robinia (black locurt only) ".
Salix (Babylon wooeeping willow only) ::
Syringa (lilac) ';
Tecoma ca-)onsis '
Thuja orientaliss (Chinese arborvitae) '
Xanthoxylum (prickl:.-ash) ,
Zi zf7Laus (Jujube) ,
Since, so far as Imown, Parlatoria chinonsis is not widely distri- ::
buted in the United Stat-.s ,and is a uDmber of La destructive group of plant .i
post.s, it is essential that th- a-rea in which it is est..blished be known ,:
so that its in'coa.z and s-orca., can be restricted or prwvnted, a.s far as .'
possible, until the status of the insect af a ?.C?t, the need for a control ..
program, and. the basis for control can be established. Accordingly, surveys e
have been condu-icted by the Bureau of Entomology and Plant Quarantine in
cooperation with the Missouri State Department of Agriculture, the Missouri "
Agricultural Ex-)arimcnt Station, the city of St. Louis, and the Missouri
Bota-nical G.trdr-. to delimit the infestation and to determine the host plants a U
cn '-hich it occurs. Studios have been made by tho" same agencies to de-
termino the seo.sonal history, habits, host-plant rol.-Ltions, and natural ,
cn-mics, rzi- to develop possible control rm3amisuros. Control and regulatory
activities to r-ctrict and prevent the spread of the scale have been con-
duiictd by-- the .s-s.uri State Department of Agriculture, and a survey in "'
E.s;t St. Louis, Il., .'ns conducted in 1A41 in cooperation with the .,
Illin-.is Stato Dtpo rrront of A!:ricualture. Information obt:%inod prior to':
rovcal.-_r 1942 is sumra.rizcd and brought up to date in this circular. :
i : :'..
., ., "
The plants in the following list have been found as hosts of Parlatoria
chinensis in St. Louis. Those most commonly infested or which appear to be
satisfactory hosts of Parlr-toria chincnsis are marked with an asterisk.
Aesculus hippocastanum (common horsechestnut)
Aesculus carnea (red horsechestnut)
Alnus sp. (alder)
Aralia spinosa (angelica tree)
Aronia arbutifolia (red chokeberry)
Asimi:.,r triloba (papaw)
Betula nira (river birch)
Betula populifolia (gray birch)
Betula spp. (birch)
Broussonetia papyrifera (paper mulberry)
Caragana arborescens (Siberian pea-tree)
Catalpa bignonioides (common catalpa)
Catalpa bungei (umbrella catalpa)
Catalpa ovata (Japanese catalpa)
Catalpa speciosa (western catalpa)
Celtis occidentalis (hackberry)
Chaenomeles lagenaria (flowering quince)
Chaenomeles spp. (quince)
OCOUT C T T I STATES
OC03131C 'U OMPT T1-2 UMlTIED STATES
Parlatoria chinonsis is not yet knownim to occur in the United States
outside the city and county of St. Louis, Mo. Surveys conducted during December
L940 and January1941 and from Novomber 3, 1941, to March 31, 1942, have resulted
in jts being found on plants in the Missouri Botanical Garden, Tower Grove,
and Forest Parks, on 1,274 other properties in 173 blocks in the city of St.
Louis, a.nd on 2 properties in a small area (partly in Brentwood and partly
in Maplowood) in St. Louis County. It is estimated that the area in which
Infested plants have been found, together with a narrow border area in which
infestations have not beeoon found, covers about 8 square miles in the city
of St. Louis. Surveys are being continued to obtain fiArthcr information on
the status of the infestation in the known infested area nnd to delimit more
exactly the area of infestation.
Chionanthu.s virginica whitte fringetree)
Oladrastis lutea (yellow-wood) .. :
Cornus asperifolia ':
Cornus flava ..' "
Comnus florida (flowering dogwood) "
Cornus nmaLs : .
,.*'.. '* ,.
Corpus sarn.inea e: a ,'
----~~~, -- --- ., :,.,
Cornus spp, (dogwood) '
--- ," "'-;'. : ';".',>. ":^
.' ^:.t... ::;::..;' ".,
Corylus avelluna (filbert) :;,:i
Cotinus coggygria (purple smoketree) R'."
Cotoneaster acutifolia (Peking cotoneaster) A^^:i
------------------ ---------- ", ..'.: A ,--
Cotoneaster horizontalis ';
Cotoneaster lucida '
Cotoneaster praecox :
- -- --. ....-- 44-:1?
Cratasous mollis (red hawthorn) :.'
Crataegns oxyacantha (English hawthorn) '::
------~~ ---- ^ ..
Cratae2'us phaenoprumn (Wash.ington hawthorn)
Crataeias app. (handt1.orn) '
Diospyrcs virginian,\ persimmonn)
Elaeagnus ang.stifolia (Russian-olive) -'.'*
Euonyrmis alatus (winged euonTmus)
Eron.'ymus bungeana (vinterberry) ..
Euon:,us .mro-oaeus (snindle tree) '':
5iion,-mus yedoensis (wahoo) .::
E:.o chorda grand flora (pearlbush) .V
Forsythia fragrant ssirna :
Forsythia spp. (golden bell) : '
"' *'.'. . .
.: ..: : : '
Fraxinus americana (white ash)
F raxinus lanceolata (green ash)
G|' Gleditsia aquatica (waterlocust)
Gleditsia triacanthos (common honeylocust)
Halesia carolina (silverbell)
Hanamelis virginiana (witch-hazel)
i Hibiscus syriacus
Hibiscus spp. (althea, rose-of-Slharon)
Ilex decidua (deciduous holly)
Ilex opaca (American holly)
SfIlex verticillata (holly, comaion winterberry)
( Juglans nigra (black walnut)
Koelreuteria paniculata (varnish-tree)
S Ligastrum ibolium
S* Liguastnrun ibota
Ligu-strum ovalifoliurn (California privet)
Ligustnm regelianum (regel privet)
Ligustr,:iia spp. (privet)
LineLora benzoin (spice bush)
Lonicera spp. (honeysuckle)
Maclura pomifera (Osage-orange)
* Malus baccata (Siberian crab)
" Malus floribunda. (flowering crab)
* .Malus pumila (apple)
* Malus spp. (apple, crab apple, flowering crab)
Phellodendron anurense (Amur cork tree)
* Prunus amygdalus (common peach)
* Prunus ermeniaca (apricot)
* Prunus ceresifera pisserdli (purplelepf plum)
* Prunus Padus comnutatis
* Prunus salicina (Japanese plum)
* Prunus serotina (black cherry)
* Prunus serrulata (Oriental cherry)
* Prunus tomentosa (Nanking cherry)
* Prunus trilobe (flowering plum)
* Prunus spp. (apricot, cherry, flowering Jlmond, pesch, plum)
Ptelea trifoliata (waferash, hoptree)
Pyracantha op. firethornn)
* Pyrus communis (pear)
P Rhamnus cathartica (common buokthorn)
Bhamnus frangula angustlfolia
Rhodotypos kerrioid.es (jetb'ead)
Rhus canadensis fragrantt sumac)
: .. '. .
S* *< .'?
Rfhus typhina (sta ghorn sumac)
Ribes auroum (yellow flowering currant)
Ribos spp. (currant)
Robinia hispida (rose-acacia)
Rosa rubiginosa (swmotbriar)
* Rosa ragofa
Rosa spp. (rose)
Salix babylonica (Babylon weeping willow)
Sambucus sp. (aldeor)
Sassafras albidum (sassafras)
Soph or:a japonica (pagoda tree)
Sorbus aucuparia (white mountain-aPsh)
Symphoricarpos albus (snowberry)
* Syringa josikaea (Hungarian lilac)
* Syringa nanceiana var. floreal
* S;yringa oblata
* Syringa reflexa
* Syringa tomentella
J~~~ t ..,
Syringa va.lgaris (common lilac) .
Syringa spp. (lilac) -;|
Tamarix gallica *
Tilia americana (American linden) :
Tilia europaea (large-leaved basswood)
Tilia heterophylla .-
Ulmus amricana (American elm) : "
U1.iu.s :muiila (Chinese elm) ..:
Viburnum amnericana (American cranberrybush) 14:'-
Viburmium cas'sinoides (withe-rod) ..
.. ': ,;:
Viburn-tu lantana (wayfaring-tree) ".
Viburni,;i lentago (sheepberry) ''
Viburnrun prnifoliumn (blackhaw)
Viburnum s)p. : '
Xanthoceras sorbifolia (Chinese buckeye)
Zelkova serrata ,
.... : '' :} l "
Infested plants reported as Forestiera sp. and Ginkgo biloba on page 2 ..
of mimeographed circular 3-535, dated April 1941, are now believed to have :
been misidentified, and these should not be considered as proved hosts of *
this scale inll the United States. .
Althea, privet, and lilac have booeen most commonly found infested, but, -,
since they occur nore frequently and in greater numbers than other plants'- ;
that appear to be satisfactory hosts, they cannot be considered necessarily -'
ns the greatly preferred hosts. Species of plants other than those so indi"' .'
cated rmayr be satisfactory hosts of Parlatoria chinensis, but they occur too .i
infrequ rtlt- in the infested area to provide sufficient information to per-,,,
mit their classification as such at the present time. Plants present, in i
the infested arca in moderate to large numbers that do not appear to be .:'
hosts of this scale include barberry, maple, mockorange, poplar, and mrdst, i
if not' all, evergreens. :
L .1~4 J
** ,... .:.. a>
/ DESCRIPTION 0 PAIA RIA0R CHI! NSIS MABLATT 2/
W. Within or around the present known area of infestation, Parlatoria
chinensiss can probably be differentiated superficially from other encountered
species of armored scales by the following characteristics: Adult female scale
Sflat or only very slightly convex, short elliptical to oval, length up to
1.25 mm., exaviae marginal at the anterior end of the scale and covered with
a.tin, easily detachable film of secretion, no trace of a cone or a ring
i and d6t arraigemaent of the scale surface; adult male scale, '-rhich usually
occurs along with the female, distinctly elongated and narrow, with the larval
Sexuvia'at the end, length up to 1 ms., the secretionary material not loose,
scale not carinated, the texture approximating that of the female scale; body
Sof mature female when exposed not peg-top shaped or turbinate, as with, the
aspidiotines which are most apt to be found in the area of infestation in-
" stead, the head end appearing somewhat narrowed and protuberant because of
the presence of slight notches, one on each side of the body, about one-fourth
of the way back from the head.
Color of the live adult female light purple, becoming darker as it be-
comes older; of the dried adult female, strong reddish brown. Scale covering
Sending toward coloration of host bark, more so on some hosts than on others.
S.. The two most valuable indicators of the presence of this scale on plants
ln the present known.infested area are (l) the purple color of the adult female
a:;and (2) the ventral molt skins of the males, which remain as tiny white specks
*''on infested plants long after the male covers slough off. Those specks have
Seen aptly termed "footprints," and are not so characteristic of any other scale
insect encountered in the St. Louis area as they are of Parlatoria chinensis.
Microscopically the insect has a strongly triangular n-ygidium super-
I ficiall- suggesting that of the San Jose shale (Aspidiotus perniciosus Comst.),
Sbut it is in no way related to this insect. For discussion of species of
Parlatoria hitherto known to occiir in this country, see Ferris, Atlas of the
Scale Insects of North America, 1937, pages SI-84, SI-90; and 1942, pares SIV-
400-405; and Morrison, Taxonomy of Some Scale Insects of the Genus Parlatcria
Encountered in Plant Quarantine Inspection Work (U.S. Dept. Agr. Misc. Pub. 344,
1939, 34 pp., illus.). From the s-oecies dismicussed in these references, chinensis
Sis readily differentiated by the following combination of characteristics: Duct
tubercles present on head and opposite anterior rpiracles; a tubular duct between
median lobes, this relatively small and slender; all dorsl.1 ducts much reduced in
size and number, small and inconspicuous, only a few (perhaps a hlf-dLozcn) on
each half of the pygidium strongly produced, triangular; ;.-Idian lobes large, close
Together, triangular, outer margins crenulate, no intermediate plates, second
lobes much smaller, also asymmetrical, notched or faintly crenulate externally,
other lobes wanting; plates greatly reduced in number and size, slender, tapering
Sto an approximate point, 1, obscure, between first cand second lobes, 2 beyond
the spine outside each second lcbe, 6 to 8, short and obscure, scattered along
the rest of the pygidial margin on eaLch side, this in contrast to the relatively
numerous large and conspicuous plates present in most of the other species that
have been reported from the United States; no derm pocket out-side posterior
spiracle. Among the species discussed in papers listed, prob.'.blv ei-e.rest to P.
I 2/Most.of the material in this section has been quoted verbatim from
S SISMORY m '':.t ^
.. r 4 ;:A
",kevelopment of Parlatoria cbinensis under natteil conditions has 'beo n :
determined by the examination of specimens on sampiei 6f infested plaOits taken ..
from three or more locations at regular weekly interval duiihg that part O
the year when the scale is undergoing development, and less frequently dUr1X$:
the dormant season. All specimens on each unit randomly selected plant arem'4
have been included in each examination. A sufficient number Of unit areas
selected for examination to .sfiin ume fui ra
selected for examination to furnish apfroaximately 300 specimens per sample 4.|
when all, or most, of the stages through which the insect passes in its doee..
mont were represented. Fewer specimens per sample were examinedwhen a.mare1..
limited numbsi of stagon were represented. i 'I:-
Th> seasonal devslopmont of this scale insect under natural conditiaf
St. Louis during 19-2, as determined from periodical examinations, is .
in table 1. Adult males that had emerged were not included in the record J.i|Jpg
cause of th- impossibility of accurately separating the new male cover firt i:'
the old. Consequently, since specimens of this scale do not remain in.-any 8l
immature stage very long, the data in table 1 do not indicate the proporti-nVL ,J
the sexes. However, it has been found that males predominate ovor females
about the proportion of 2 to 1. Diffnrenocs in the time and rate of doValppv$*
ment of srpcimens on different plants of the same species or on plants af ..l
different species havo been small and were apparently duo largely to differan4
in exposure. Specimens on plants in sunny locations, begin development a. tll
sooner and develop a little faster than those on plants in shaded location:.
There wero two complete generations and a partial third of Paratoria"-vs^--^
chinons-is in St. Louis in 1941 and two complete generations and a trace of al -*ll
third in 1942. Apparently only fertilized, adult, second-brood females ovorr:. .N mmm.
winter, although it is possible that a few third-brood females might reach the
adult stagz, and overwinter in some seasons. Immature specimens appear to bel '"mm
able to survive the winter. '. m 'mm
About 40 eggs are formed over a period of approximately 2 months wit,: b
the body of oeach producing adult female. They. are extruded a few at a time i'
and hatch after about 5 to 10 or 12 days. according to prevailing weather cow-...
ditions. During 1942, extruded eggs were first found April' 24 and wore pr3%
almost continuously to Octobcr 30. '
As will be noted from table 1, there is a distinct overlapptng of the ..: -.
periods during which adult females of the overwintering and first broods and :..
those of the first and second broods occur. A similar overlapping occur 1mmmmmm
the periods during which eggs, crawlers, and other developmental stages of' 'I m'
individuals of the first and second broods are present. As a result of thi..
ovcrlap-ing there is a considerable period during'the summer months when i't
viduals in each stage of development are present. 'il**3.
In 1941, first-brood crawlers were present from May 14 to early JUj,-
sjconcL-brood crawlers from near July 15 to mid-October, ahd third-brood craw'.Li.
from the last of September to near the middle of November. In 1942, datawi.-::-
table 1, coupled, with those obtained as a result of regular weekly exadlnatli
of cleared areas on infested plants in the field, indicate that first-brood 4:.mm
crawlers were present from May 1 to about July 24, soeand-brood crawlers frometl
SJu4y 10 to n:ear the p nr ne *ot+omrmv ,nrl a fm or the third brood during tb'" C;|
an.rh 1-ecfl fif CO et'.l~ ^. q.^ **;i
Crawlers were normally present on the plants in greater numbers during
the morning and early afternoon than during other parts of the lay. Theyr settle
in a comparatively short time, and do not ordinarily travel far. In special
tests, three-fourths of all crawlers that settled did so during the first hour
After their transfer to the test pl-ntsh rud all that settled did so by the
end of the fourth hour. Crawler may wander over plants for mach longer periods,
4 but if they do they usually die, and few are able to settle after the fourth
hour. In three tests no crawler settled farther than 7 inches from the noint
i at which it was placed, 67.4 percent settled within 1 inch of the point of
Stransfer, and 86.8 percent settled within 2 inches of it. In two oth-r tests
no transferred crawler settled more than 5 inches from te noint at which it
...was placed, and 86.8 percent settled within 1 inch of it.
SIt is possible to transfer crawlers from one host plant to another with-
|g out detriment, to their ability to settle, develop, or reproduce. They usually
4 settle .about some obstruction, as another scale, a crotch, bud, lenticel, bark
.. scale, scar, or other place of similar nature, although some also settle on
Smooth surfaces. They do not settle r;.adily or very successfully on the "ore
Ssucculent growth of the current season or on plant surfaces that are hairy or
Shave thick, rough bark. The scales have never been found settled on fruit and
only rarely on foliage in the field, and none ever settled on fruit or foliage
Sas a result of transfers made in the laboratory.
INCREASE AID SPRED
SObservations in 1941 indicated that Parlatoria chinensis could increase
During the second-brood period from a low population level so low that they
Could scarcely be seen with the unaided' eye to a moderate or hih population
Level at which they were easily visible.
SIn 1942 the change in size of scale populations from brood to brood and
.for the season as a whole was determined by comparisons made on 73 conparab2e
Sample areas on 13 plants in 4 locations. The comparisons were on number of
live, mature or nearly mature, adult females that survived the winter, the
number present near the end of the period of first-brood development in July,
and the number present near the end of the period of second-brood develop-
menrit in October.
The scale population on the sample areas decreased from an average of
4.87 to 3.48 specimens per square centimeter, or 28.5 percent, during the de-
velopmental period of the first brood; increased from 3.48 to 7.02 specimens
per square centimeter, or 101.7 percent, during the developmental period of the
second brood; and increased from 4.87 to 7.02 specimens per square centimeter,
or 44.1 percent, during the season as a whole. Probably because of lower mean
Temperatures and greater rainfall during 1942, the scale population did not in-
crease so much as it did during 1941. Weather conditions during May 1942 were
r especially unfavorable for the hatching of first-brood eggs and emergence,
settling, and development of crawlers, with the result that mortality of the
insects in these stages was high. During the last half of the second-brood
period in August and September the mean temperature was approximately 5 degrees
below that for the corresponding period in 1941, a condition which anopeared to
o rtail second-brood activity.
TAT PLANT BOA
Parlatoria chinensis is Known to be spread by the removal of Infested :
plants from ont plaeci to another, by the natural movement of orawlera from
infested plants to other nearby plants, and by air movement. It is also prob-
able that it can be spread by other insects and by birds.
Durin theu-. 1942 season crL., 0.rs ware captured on sticky traps located i
as far as 26 fe..t from the noarast !'noin infested -lant, and adult males were *s ;
captured c.s far ac 42 feet from the nearest lmnown infested plants, indicating .
that this scale can be and is disseminated by air movement. Young applo, peaclhq:,.
pear, plun, and cherry trees that w.:re uninfostod when set in an experimental P'.:
nursery planting in the spring of 1942 wore found infested when examined in the ..
fall of 19-12. Since som.oe cf these ynung trees we-ro 6 to 8 feet from the
nozar.-st inf.-tc. "-la. -ts, a%:-d some of the infestations wore well up in their :;
.2rrchu'z, it s:..is --r.'bable that they becameno infested by wind-bloim crawlers. ":
1,TATUE 'OF INJURY :
Sufficient observations have not yet besn made for an opinion to be '-
for.-3.d as to the ,otentialities of Parlatoria chinensis as a pest. Sxperimonts
are uLnder va:y whichh it is expected, will eventually ikrnish such information, :
The writers have observed a few plants which they believe to have been
killed by- this scale, and have also observed young aple trees in which local
injury was cause, by only a few specimens of the scale. On these trees tho
bark tissue first becamec red and then died at' and about the points of infostationv[
Observations of infested plants indicate that injury ordinarily develops '1
slo,.ly t.nd gradually over an extended period and is first bvidont ir. the form I
of woak, sparse folia-ge. Later, small limbs may be killed.
INATURAL EMIS S
.!,.tural ernmies hav- not been found present in sufficient nunbors to
indicate th'-.t theicy can be expected or depended upon to holdC infestations of
t'-is ins~ct i' C,.hc':. The most ~n-portant ao.-ar to be a predacious nite,
He.isarcwptec t.lus Shiner (determined by H. E. Ewing), and a parasite, Aphytis
sp. determinee. by A. B. Gahan).
METHODS OF CONTROL
Experiiaents have been conducted, and others are underway or planned, to:
develo- a suitabjle method or methods for the control of Parlatoria chinensis.
Spra:r task's have been limited, for the most part, to oil sprays with and with-
out added. to:dxicants applied during the dormant and delayed-dormant periods and .
during the stuinLer. Commercial, but not conrolete, control has been obtained in.-
all --r-Iods 'ith concentrations of oil that have not caused noticeable plant -. :
Inj-r-, but furt:ier 'ork is essential to determine the most satisfactory "
materials am,:, concentrations. In addition, experiments with tent fumigatAon,
ai.: o:.odifications of it, are being conducted in the field with methyl bromide
a:'d calcium cyanide. Information conce-rning this method of field treatment is '
incompl-te, and :.ore data are needed before its practicability can be determined. r
i ... .
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- 13 -
miant and Delayed-Dormant Applications
On 'the basis of present information, a 4-percent concentration of a
.properly emulsified dormant-type oil is recommended for use to control heavy
to encrusted infestations during the dormant and delayed-dormant periods, and
a 3--percent conenontration is recom7a-end.ed for use to control medium or lighter
'" infestations, .fith regard to the timing of dormant applications, it is be-
'..o lived that the commonly recommended practice of spraying only when the tempera-
|/ ture is above 40 F. should be followed.
Other factors being equal, it has been found that any given oil will
'4. effect about the same degree of control of this scale on one plant species as
.. Oils whoso specifications fall within the range of those of oils co.m-:orly
recommended for dormant use have pro-roved equaally effective when tested for the
Control of this insect. On the other hand, the type of emnlsifier used ha.s
SbdoiIfound to be an important factor influencing the insecticidal efficiency of
Sthea..oils, and the quick-breakWing t:Tpes of oil emulsions have beoon more effective
than more stable types. Sufficient tests have not yvt boen made, hovc.ir, to
jusBtify the rccor.iondation of any particular emulsifier or typc of iem-ulsifier.
The addition of such materials as rotenone (in the form of cube resins)
and dinitro-o-cyclohexylphonol to low concentrations of oil has increased their
efficiency markedly, but the exact quantities of these materials needed has
not yet been determined.
.. Sunter Applications
.: In all tests of oils suitable for use in summer applications, a 5-percent
ci concentration of oil has been highly effective, a 2-percent concentration has
i. been moderately effective in some instances and highly so in others, and a
1-percent concentration has been ineffective. Oils within a viscosityr range
of 80 to 100 seconds Saybolt at 100 F. and with unsulfonated residue contents
Sof 90 to 95 percent by vol'u:e have bee:-, more ofi'ective than lighter ones with
Sa viscosity range of 55 to 62 seconds Saybolt at 100 F. and unsulfonated
residue contents of 80 to e5 percent by volume, and they have b2n2i as effective
Sas the one heavier oil tested.
Applications made shortly after the pal,-_ period of omorrgnco and settling
Sof first-brood crawlers and at the corresponding period of omw.rgonce aCnd
Settling of second-brood crawlers were about eq-ially effective and more so than
those made in thie interval between tho period of first-brood and second-brood
Activity, when a majority of first-brood specimens were prosont as aJ.ult fe-
Smales. Two applications of 2-percent light-medit sumz.or oil mado about 1
month apart reduced an infestation more than did one application at other time.
... In all tests made to date, rotenone in the for.-m of cube resins h'as
markedly improved the efficiency of low concentrations of light-m:di'um. sv mnzer
Soils when used to effect control of this scale. One-percent li:-ht-medium sumamer
oil containing from 0.01 to 0.02 percent of cube resins (cube resins contained
S16.4 percent of rotenone) has been nearly equal in efficiency to 3 percent of
the same oil without added toxicant. Also, a 1-percent concentration of a light-
It medium sum-aer oil which contained 0.05 percent of rotenone in the stock emulsion
has given a high degree of control. Rotenone, however, is not available at thea.:.
present time for the sOraying of fruit trees, and it is also considered de- .
sirable that further tests be conducted before definite recommendations are
made for its use.
On the basis of present information, if it is considered necessary or
desirable1 to sur-nlozicnt dormant or delayed-dormant applications with. summer
s.ra--s for t"z control of Parlatoria chinensis, it is recommended that a :
conc orati" of 2 recentt of an oil having a viscosity of from 80 to 100
seconds Sayrbolt at 1000 F. and an unsulfonated residue content of from 90 to ,I
95 percentt by volume be applied at or near the peak period of first- or secondU-;:,
brood crarler emergence and settling, or at both periods if the degree of infesr
motion warrants. *
EPADICATION AZI C01iTROL
During the spring and sTinier of 1942, a control program designed to -
eliminate all 1_noim infested plants outside the primary infested area was -,. .
carried out by of-.icials of the Missouri State Department of Agriculture. eor.-'".
mission to remove infested plants was solicited from home owners and othersoil..: o.
whose properties such plants had been found in the area involved, and the re-.-'
sponse was so favorable that, as far as was known at the time, all infested
plants were removed from all parts of the infested area in the city of St.
Louis outside that bounded on the north by Vandeventer and Folsom Avenues., on
the east b:- Spring Avenue, or- the south by Arsenal Street, and on the west by
Kingshighway. In addition, all infested plants were reaioved from the two
infested Dropcrties on which such plants had been found in St. Louis County.
The total number of '-noun infested plants wa5 reduced by approximately 4 percent"
and the number of lmo'.n infested properties by about 15.5 percent.
The reioval program was supplemented with a spray program designed to
reduce the size of, or eliminate, if possible, scale infestations that might
have boon overlooked in the survey. A 3- or 4-percent dormant oil emulsion.
was applied in the spring of 1942 to all possible host plants on many properties..
fro- which all imo-m infeFted plants had been removed, and a 2-percent summer
oil emulsion vas similarlT applied during the period of emergence and settling
of first-brood crawlers. In some instances possible host plants on properties
adjoining infested ones were sprayed also.
.The n!oven.ent of woody -plants and plant parts from within the infested
area to an-, noint outside of said area has been regulated and restricted by
a quarantine invoked by the Missouri State Denartment of Agriculture, which wap
made effective April 18, 1941, and revised April 18, 1942.
Expqerimental fiVmigation work is being conducted by the Division of Con-
trol Investigations, Bureau of Entomology and Plant Quarantine, for the purpose
of developing a treatment of plants or plant parts infested with Parlatoria
chinensis that can be depended upon to destroy all stages of this insect, with-
out injury to the plant" so that such material can be subsequently released from :l
quarantine restrictions. .4
. Although the fumigation of plants with methyl bromide has not as yet
been authorized for this -urpose, the following schedules appear to be satis-
factory for treatment in fumigation chambers:
21/2 pounds of methyrl bromide per 1,000 cu. ft. for 2 1/2 hrs. at 80 7.
3 pounds of methyl bromide per 3.,000 cu. ft. for 2 1/2 h'rs. at 70 F.,
4 pounds of methyl bromide ner 1,000 cu. ft. for 2 1/2 :-rs. at 600 F-
4 pounds of methyl bromide per 1,000 cu. ft. for 3 1/2 hrs. at 50 0.
: 4 pounds of rethyl bromide rer 1,000 cu. ft. for 4 1/2 hrs. at 40 F.
There is a seasonal period, beginning apparently .iith the approach of
cold weather, when Parlatoria chinensis becomes irncreasingly rnore resi .tant to
unaigation, even though the temI-erature has not ch-an-:ed. This "ariod extends
into MIarch, at which time the insects seem to lose t.is resistance to some
degree. This vari-ltion cf resistance has been observed fTr about 15 month-s,
and there is evidex.ce thi-t it may vary in intensity from yar to year. Fl.i-
gation experiments are being continued for th3 purpose of' obtaint-nl. additional
data on this s-3asonal cycls. If these annual cycles of re stance 'rariatin
shall be found to have a reasonable ccnform-tion, funig:.tion sch'd'las La- be
determined for the period of lower r-sistanc3 in order to reduce thj time of
exposure or the dosage and in turn wi&'n the narzin beti.v.s-n comnlotc in!rect
mortality ancL --jlant injury.
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STATE PLANT BOAW
June 1943 E-595 (Supplement)
United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
PARLATORIA C1HI'E..!IS i"F:LATT
At the time the manuscript for Circular E-595 was prepared
Parlatoria chinensis was not known to occur in the United States
outside the City and County of St. Louis, 1o. On January 26,
1943, this species was collected by an Inspector of the Florida
State Board on Ficus sp. in a nursery near Boynton, Fla. 11'terial
was forwarded to the Bureau and the determination was confirmed.
On receipt of this information the Florida authorities placed
the nursery under quarantine.
The State Plant Board of Florida undertook an intensive sur-
vey to determine the possible distribution and the host plants
of Parlatoria chinensis that might be involved in Florida.
During the latter part of February Mr. Howrard Baker, in charge
of the work the Bureau is doing on this scale insect in St. Louis,
visited Florida to observe the infestation and to discuss with
the Florida authorities the results of the work in St. Louis on
the plant host habits, life history, and control of Parlatoria
The present distribution of the scale in Florida (June 1943)
is confined to several points in Palm Beach and Broward Counties
on the lower East Coast, and one point in Lee County on the lower
West Coast. It is very interesting that up to this time all
the infestations found in Florida occur on various species of
Ficus. In the inspection work, particular attention has been
given to the edible figs (Ficus carica) and to date no scale has
been found infesting these troops. The State of Florida is con-
tinuing its efforts to determine the extent of the infested area
and to discover additional host plants.
UNIVERSITY OF FLORIDA
3 1262 09224 6973