Parlatoria chinensis Marlatt, a scale insect recently discovered in the United States


Material Information

Parlatoria chinensis Marlatt, a scale insect recently discovered in the United States
Physical Description:
5, 2 p. : ill. ; 27 cm.
United States -- Bureau of Entomology and Plant Quarantine
United States -- Dept. of Agriculture. -- Division of Insect Identification
United States -- Dept. of Agriculture. -- Division of Domestic Plant Quarantines
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:


Subjects / Keywords:
Scale insects -- United States   ( lcsh )
Parlatoria -- United States   ( lcsh )
federal government publication   ( marcgt )
non-fiction   ( marcgt )


General Note:
Caption title.
General Note:
General Note:
"April 1941."
Statement of Responsibility:
prepared by the Division of Domestic Plant Quarantines in cooperation with the Division of Insect Identification.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030270386
oclc - 778715603
System ID:

Full Text

E-535 DER ENT April 1941



Prepared by the Division of Domestic Plant Quarantines
in cooperation with the Division of Insect Identification


In April 1940, during an annual inspection of a nursery sales
lot in the city of St. Louis, Mo., an inspector of the Missouri
State Department of Agriculture collected specimens of a diaspine
scale of doubtful identity. Specimens were submitted to the Bureau
of Entomology and Plant Quarantine for identification and were sub-
sequently determined as Parlatoria chinensis Marlatt, a scale in-
sect not heretofore reported as occurring in the United States.
A preliminary survey conducted by the Missouri State Department of
Agriculture during the spring and summer of 1940 disclosed infes-
tations of the insect in the Missouri Botanical Garden and Tower
Grove Park, and radiating therefrom for a distance of several
blocks. Infestations were found on several different species of
plants, including althea, lilac, privet, buckthorn, red choke-
cherry, and purpleleaf plum.

Available information on the occurrence of this insect in
foreign countries indicated that it might be of potential economic
importance if disseminated in this country. Therefore, in order
to obtain information as to the extent to which the insect had
become spread, the Bureau of Entomology and Plant Quarantine co-
operated with the Missouri and Illinois State Departments of Agri-
culture in a survey of St. Louis and vicinity during December 1940
and January 1941.

Occurrence in the United States

The preliminary survey conducted by inspectors of the Missouri
State Department of Agriculture, during the spring and summer of
1940, established several apparent foci of infestation located in
Tower Grove Park and the Missouri Botanical Garden. When the
survey was re-umed in December, in cooperation with inspectors of


the Bureau of Entomol-:y and Plant Quarantine, these apparent foci
were used as starting pints, and all properties in all directions
were intensively ri'.-:.te. to points several blocks beyond the
properties on which t"e last infestations were found. In addition,
inspections were also r.a. of other parks and plantings throughout
the city. Inspector: of the S-ate of Illinois cooperated in a
survey of East St. Louis, Ill.

These sur,,ve;s :veal. infestations of the scale on approxi-
mately 850 properties located in 109 city blocks in the vicinity of
the Missouri Botanical C.n, .r Grove Park, and Forest Park.
Infestations were found on the following plants:

i Aesculus hiLp::astanum (common horse-chestnut)
Arcnil arbutifolia (red chokecherry)
Asimina triloba
Betula :'igra (river birch)
Broussonctija Ca'-vrifera (paper mulberry)
Cornus spp. (dogwood)
Corylus avellarra (hazel bush)
Cotoneaster acutifolia (Peking cotoneaster)
CrItae~us spp. (hawthorn)
El^ae mi a-.,.ltijfolia (Russian olive)
Een n.,c Srpl. (stras'berry bush, spindle-tree)
Forestiera sp.
Gi-.1 Ullic!. ( tree)
Harmicl .I.l v ir.r-- : u i,] (witch-hazel)
Hibiscls j.t. (althea, rose of Sharon)
Liau'trurn sprp. (privet)

M .,2.Iurn rromifera (Osage orange)
f._.ll f ..- r.'. -n1p rI. nse (Amur cork tree)
Prunus :zpp. (?l.crry, peach, plum)
-Ptelea Iri- fol i_.-a (hop tree)
EP,.L..u (f:an, wild crab, apple)
Pfr-c.-,.thl sp. firethornn)
Rhamnus l-,l ,n i buckthornorn)
iil, spp. (srac)
Ribes -pp:' (clrroirnt)
r,1, l-'i hil',.iL'Ta (roze acacia)
Rosa I",p. (rose)
*-l> LL.,l ul',, (weeping willow)
._i.'L'.l ,,.,. ' ,'' i
1-v : 1'. r i'i'_L'1. iL'_. (snowberry)
',' r I L' ,_spp. (lilac)
T11i L... i, (lar r.-l :.aved basswood)
V ii: ,ii m -'r '
Zr 11- .' ,. ,',.

- 3 .

Occurrence in Foreign Countries

In 1908, C. L. Marlatt described Parlatoria chinensis from
specimens collected on crab apple at Tientsin, China, in 1901.
Notes appended to the original description mention its also having
been collected at Taira, Japan, upon an unknown host, and at Chefoo,
China, on Hibiscus species. It has since been reportedd from China
by Meyer in 1907-08, and from Egypt by Hall in 1922-23. Hall
reported the insect as fairly coml,. n in Upper Egypt on such plants
as Justicia alba, Tecoma capeisis, mountain eboniy, oleander, black
locust, fig, olive, plum, pear, apple, and weeping willow. Since
1916, inspectors of the Federal Horticultural Board, and, later, of
the Bureau of Entomology and Plant Quarantine., have intercepted this
insect from importations of plants having their origin in China,
Japan, and India. The following plants have been mentioned as host
plants of the insect in published records of the collections of the
insect in foreign countries, and from plant importations:

Bauhinia (mountain ebony, orchid tree)
Cassia fistula (pudding-pipe tree, golden shower)
Ficus (fig, etc.)
Hibiscus (rose-mallow)
Juglans (walnut)
Justicia alba
Malus (crab apple only)
Nerium (oleander)
Olea (olive)
Prunus (plum only)
Pyrus (flowering varieties of pear only)
Robinia (black locust only)
Salix (weeping willow only)
Syinga (lilac)
Tecoma capensis
Thja orientalis (chinese arborvitae)
Xanthoxylum (prickly ash)
Zizyphus (jujube)

Habits of the Insect

As far as is known, from limited observations in St. Louis,
the scale overwinters in the adult stage, eggs hatch late in May or
in June, and immature forms have been observed to be active about
July 1, reaching a peak of abundance about August 1.

A description of this insect, supplemented by drawings,
(figs. 1 and 2), is included in this publication to provide a
readily available reference for persons interested in making surveys
for the insect, or those who may come in contact with scale in-
sects of doubtful identity suspected of being this species.



Although experienced entomologists will probably be able
to make determinations of this species with reasonable aCssurance
after observations of specimens or known infestations in the field,
critical recognition of the species will necessarily be dependent
on proper e:xamii.ation of microscopic preparations.

The Bureau of Entomology and Plant Quarantine, V.'ash'ington,
D. C., is interested in receiving specimens for identification and
records of infestation. It is suggested that material bearing
this insect in any stage be fumigated or otherwise treated prior
to shipment.

SDescription of Parlatoria chinensis Marlatt

Within or around the present known area of infestation this
species can probably be differentiated superficially from other
species of armored scales encountered by the following ch.aracter-
istics: Adult female scale flat or only very slightly con.vex, short
elliptical to oval, length up to 1.25 miii., exuviae marginal at the
anterior end of the scale and covered by a thin, easily detachable
film of secretion, no traces of a cone or a ring and dot arrangement
of the scale surface; adult male scale, which usually occurs along
with the female, distinctly elongated and narro.'. v.,.th the larval
exuvium at the end, length up to 1 mm., the secretionary material
not loose, scale not carinated, the texture that of
the fc,..le scale; body of the mature female when expose 3 not peg-
toppe": -l'aped or turbinate, as with the aspidiotines which are most
apt to be fz,,..1. in the area of infestation, install the I.--ad end
appear., somewhat narro-,e:1 and protuberant because of the presence
of slight notches, one oin each side of the body, abc.,t one-fourth of
the way back from the head.

Color of the female scale on the most freq-:.;-.tly reported
host, althea, a dirty gray; of the male scale apprc.:-:_L.ately the
sar,-e; of the dried adult female, strong reddish brov..r. Scale c.over-
itr,, probably tov-.ard coloration of host bark.

In heavy infestations the J.incts are closely cr"..' 1 *o.0 the
scretionary prr e:rigs prc cjciderobly modified ii. a!:pe :\.- ap-

Microscopically the ir.scct has a strongly trl.:,,u! r' py-
gidium, LUpcrficially suggesting that of the San Jose s:.cole, but it
is in no way related to this iiisoct. For discussion of .t-ccies of
Parlatoria hitherl.o 1;icown to occur in this ccu:itiy,', :*..c. Ferris,
Atlas of the Scale Insects of North America, 1937, [ SI-84,
SI-90, and Morr.i, ::., U. S. Department of Agriculture ri:-..-,,llaneous
F. lici1tion Io. 344, 1939, 34 pages. From the specii `i.-.icus-sed
in 'l..--. refec i cte--s, clirensis is readily differcntiatl..'1 by the
followiL,. kU .bii.atioi, of characteristics:


Duct tubercles present on head and opposite anterior
spiracles; a tubular duct between median lobes, this rela-
tively small and slender, all dorsal ducts much reduced in
size and number, small and inconspicuous, only a few (per-
haps a half-dozen) on each half of the pygidium strongly
produced, triangular; median 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 to an
approximate point, one, obscure, between first and second
lobes, two beyond the spine outside of each second lobe, 6
to 8, short and obscure, scattered along the rest of the
pygidial margin on each side, this in contrast to the rela-
tively numerous large and conspicuous plates present in most
of the other species that have been reported from the United
States; no derm pocket outside posterior spiracle. Among
the species discussed in papers listed, probably nearest to
cinerea Hadden.

: ." ".;',,\- -



Figure l.--Parlatoria chinensiB Marl.: A, Adult female outline,
dorsal at right, ventral at left, x120; B, male (left) and female
(right) scales on althea, x45; C, adult female, pygidium, dorsal
at right, ventral at left, x460.




Figure 2.--Scales of (A) Parlatoria chinensis Marl. from peach,
male (left) and female (right); (B) Aspidiotus perniciosus
Comat. from apple fruit; (C) Aspidiotus ancylus Putn. from
maple; all x45.

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