LI1 
 
 \ DETRIMENT <? A P ril 1941 
 
 OF 
 
 AGRICULTURE 
 
 BUREAU OF 
 ENTOMOLOGY AND ,'/ 
 PLANT QUARANTINE 
 
 PARLATORIA CHINENSIS MARLATT, A SCALE INSECT 
 RECENTLY DISCOVERED IN THE UNITED STATES 
 
 Prepared by the Division of Domestic Plant Quarantines 
 in cooperation with the Division of Insect Identification 
 
 Introduction 
 
 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 Pa rlatoria 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 resumed in December, in cooperation with inspectors of 
 
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 the Bureau of Entomology and Plant Quarantine, these apparent foci 
 were used as starting points, and all properties in all directions 
 were intensively inspected to points several blocks beyond the 
 properties on which the last infestations were found. In addition, 
 inspections were also made of other parks and plantings throughout 
 the city. Inspectors of the State of Illinois cooperated in a 
 survey of East St. Louis, 111. 
 
 These surveys revealed infestations of the scale on approxi- 
 mately 850 properties located in 109 city blocks in the vicinity of 
 the Missouri Botanical Garden, Tower Grove Park, and Forest Park. 
 Infestations were found on the following plants: 
 
 Aesculus hippocastanum (common horse-chestnut) 
 
 Aronia arbu tif olia (red chokecherry) 
 
 Asimina triloba 
 
 Betula nigra (river birch) 
 
 Broussonetia papyrifera (paper mulberry) 
 
 C ornus spp. (dogwood) 
 
 Corylus a ve liana (hazel bush) 
 
 Co toneaster acutifolia (Peking cotoneaster) 
 
 C rataegus spp. (hawthorn) 
 E l ae a gnus angustifplia (Russian olive) 
 
 E uonymus spp. (strawberry bush, spindle-tree) 
 
 Forestiera sp . 
 
 Ginkgo b iloba (maidenhair tree) 
 
 H amamelis v irginiana (witch-hazel) 
 
 Hib iscus spp. (althea, rose of Sharon) 
 
 L igus trum spp. (privet) 
 
 L onicera chrysantha 
 
 Madura p omifera (Osage orange) 
 
 P hellodendron amurense (Amur cork tree) 
 
 Prunus spp. (cherry, peach, plum) 
 
 Ptelea trifoliata (hop tree) 
 
 Pyrus (pear, wild crab, apple) 
 
 Pyracantha sp. (firethorn) 
 
 Rhamnus cathartica (buckthorn) 
 
 Rhus spp. (sumac) 
 
 Ribes spp. (currant) 
 
 Robinia hispida (rose acacia) 
 
 Rosa spp. (rose) 
 
 Salix babylonica (weeping willow) 
 
 Securinega ramiflo ra 
 "^ Spirae a dou glas ii 
 
 Symphoricarpos albus (snowberry) 
 
 Syrin ga spp. (lilac) 
 
 Tili - a (large-leaved basswood) 
 
 Vib urnu m spp. 
 
 Zelkova serr 
 
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 Occurrence in Foreign Countries 
 
 In 1908, C. L. Marlatt described P arlatoria chine nsis 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 reported from China 
 by Meyer in 1907-08, and from Egypt by Hall in 1922-23. Hall 
 reported the insect as fairly common In Hpper Egypt on such plants 
 as Justicia alba , Tecoma cap ensis , mountain ebony, 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: 
 
 Albizzia 
 
 Bauhinia (mountain ebony, orchid tree) 
 
 C assi a fist ula (pudding-pipe tree, golden shower) 
 
 Ficus (fig, etc. ) 
 
 Hibiscus (rose-mallow) 
 
 Juglans (walnut) 
 
 Justicia alba 
 
 Malus (crab apple only) 
 
 Ner ium (oleander) 
 
 Plea (olive) 
 
 Prunus (plum only) 
 
 P yrus (flowering varieties of pear only) 
 
 Robinia (black locust only) 
 
 Salix (weeping willow only) 
 
 Syringa (lilac) 
 
 Tecoma capensis 
 
 Thuja orientalis (Chinese arborvitae) 
 
 T hymelaea 
 
 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. 
 
 UBRARY 
 STATE PLANT BOARD 
 
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 Although experienced entomologists will probably be able 
 to make determinations of this species with reasonable assurance 
 after observations of specimens or known infestations in the field, 
 critical recognition of the species will necessarily be dependent 
 on proper examination of microscopic preparations. 
 
 The Bureau of Entomology and Plant Quarantine, Washington, 
 D. C.j 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. 
 
 Description 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 character- 
 istics: Adult female scale flat or only very slightly convex, short 
 elliptical to oval, length up to 1.25 mm., 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 narrow with the larval 
 exuviura at the end, length up to 1 mm., the secretionary material 
 not loose, scale not carinated, the texture approximating that of 
 the female scale; body of the mature female when exposed not peg- 
 topped shaped or turbinate, as with the aspidiotines which are most 
 apt to be found in the area of infestation, instead 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 female scale on the most frequently reported 
 host, althea, a dirty gray; of the male scale approximately the 
 same; of the dried adult female, strong reddish brown. Scale cover- 
 ing probably tending toward coloration of host bark. 
 
 In heavy infestations the insects are closely crowded so the 
 secretionary coverings are considerably modified in shape and ap- 
 pearance. 
 
 Microscopically the insect has a strongly triangular py- 
 gidium, superficially suggesting that of the San Jose scale, but it 
 is in no way related to this insect. For discussion of species of 
 Pa rlatoria hitherto known to occur in this country, see Ferris, 
 Atlas of the Scale Insects of North America, 1937, pages SI-84, 
 SI-90, and Morrison, U. S. Department of Agriculture Miscellaneous 
 Publication No. 344, 1939, 34 pages. From the species discussed 
 in these references, chin e nsis is readily differentiated by the 
 following combination of characteristics: 
 
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 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 cotrast 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. 
 
Digitized by the Internet Archive 
 in 2013 
 
 http://archive.org/details/parlatoriachinenOOunit 
 
Figure 1, — Parlatoria chinensis Marl.: A, Adult female, outline, 
 dorsal at right, ventral at left, xl20; B, male (left) and female 
 (right) scales on althea, x4.5j C, adult female, pygidium, dorsal 
 at right, ventral at left, x4.60. 
 
B 
 
 Figure 2.— Scales of (A) Parlatoria chinensis Marl, from peach, 
 ftale (left) and female (right) ; (B) Aspidiotus perniciosus 
 Comst. from apple fruit; (C) Aspidiotus ancylus Putn. from 
 maple; all xA5« 
 
UNIVERSITY OF FLORIDA 
 
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