J. Ent. Acar. Res.
Ser. II, 42 (3): 147-151

30 December 2010

G. PeLLIzzarI

First record and establishment of Chionaspis wistariae Cooley 
(Hemiptera, Diaspididae) in Europe

Abstract - The occurrence of the asiatic Diaspidid Chionaspis wistariae Cooley 
in europe is reported. The scale was collected on the leaves of an old Wisteria tree 
growing outdoors in the University Botanical Garden of Cluj Napoca (romania). 

Riassunto - Prima segnalazione e adattamento di Chionaspis wistariae Cooley 
(Hemiptera, Diaspididae) in Europa 
Viene segnalata la presenza nell’orto Botanico di Cluj Napoca (romania) della 
cocciniglia asiatica Chionaspis wistariae Cooley, finora mai segnalata in europa. 
La specie è stata raccolta su una vecchia pianta di glicine (Wisteria sp.) vegetante 
all’aperto ed è stata probabilmente introdotta accidentalmente insieme alla sua 
pianta ospite. 

Key words: Wisteria sp., armoured scale insects, Encarsia citrina (Craw), romania

INTroDUCTIoN

The botanical gardens are often a reservoir of alien pests due to the presence of exotic 
plants introduced from different areas of the world. The introduction of living plants 
can lead to the incidental introduction of their insect pests which, in some cases, may 
persist on their host plant in the new environment. If they are small, concealed and at 
low population levels, their presence can be undetected for years (Pellizzari & Danzig, 
2007; Pellizzari et al., 2010). 

a visit to the University Botanical Garden of Cluj Napoca (romania) led to the 
discovery of Chionaspis wistariae Cooley, an asiatic diaspidid associated with Wisteria 
plants, not yet recorded outdoors in europe. Wisterias are popular ornamentals, largely 
cultivated in europe since XIX century when W. floribunda and W. sinensis were im-
ported from Japan and China.



Journal of entomological and acarological research, Ser. II, 42 (3), 2010148

Chionaspis wistariae Cooley, 1897
Syn: Phenacaspis fujicola Kuwana, 1931 

on august 21, 2010 several white covers were observed on the leaves and petioles 
of an old Wisteria sp. tree (Fabaceae) growing outdoors, near the entrance to the green-
houses of the University Botanical Garden of Cluj Napoca (fig.1). once mounted on 
slides the specimens were identified as Chionaspis wistariae, an asiatic species so far 
not recorded outdoors in europe. 

at the collection date the following stages were present on the leaves: egg-laying 
females, eggs and crawlers. Several scales were holed by a parasitoids. empty male 
puparia, white and tricarinate, were also observed. The scales were settled along the 
main or the secondary veins of the leaflets, both on the upper and lower surface; their 
number per leaflet did not exceed 25-30, apparently without any damage for the plant. 
The scales were almost evenly distributed on the leaves of the old Wisteria tree. This 
fact, the host specificity of this species and the presence of holed covers indicate that its 
incidental introduction probably occurred several years ago, together with its host plant.

Host plants and distribution

C. wistariae develops on Wisteria species (Wisteria brachybotrys, W. floribunda, 
W. multijuga, W. nankinensis, W. sinensis) (Liu et al., 1989; Malumphy, 2010, personal 

Fig. 1 - leaf of Wisteria sp infested by Chionaspis wistariae Cooley.



149G. Pellizzari: First record and establishment of C. wistariae in europe

communication). It was described on specimens first collected in California off Wiste-
ria plants imported from Japan (Cooley, 1897). It is a supposed native of Japan and is 
present also in China. It has been intercepted several times in the U.S.a. on Wisterias 
imported from Japan, and has become established in California and Pennsylvania (Liu 
et al., 1989; Ben-Dov et al., 2010). according to Miller et al. (2005), it is not considered 
a pest over there. 

With regard to europe, between 1981 and 1990, C. wistariae was officially detected 
on six occasions at commercial plant nurseries in the UK (in the counties east Sussex, 
Norfolk and Surrey) on bonsai Wisteria brachybotrys and Wisteria floribunda imported 
from Japan (Naka-ku, Nagoya, aichi prefecture and Yokohama, Kanagawa prefecture). 
In all cases, action was taken to eradicate the scale insects under the guidance of the U.K. 
Plant Health and Seeds Inspectorate authorities and all infested plants were destroyed 
(Malumphy, 2010, personal communication). Probably C. wistariae has been incidentally 
introduced with its host plant several times from Japan to european countries, even if 
we are aware only of the above reported cases.

Notes on biology

as with other Chionaspis species, C. wistariae has a white, oystershell-shaped 
cover, 1.5-2.5mm long (fig.2); the specimens settled on the petioles are distinctly longer 
than specimens settled on the leaf. Its biology is not known in detail but, as with other 

Fig. 2 - Wisteria leaflet with the white, oyster shaped covers of C. wistariae.



Journal of entomological and acarological research, Ser. II, 42 (3), 2010150

Chionaspis species, it develops two generations/year: a summer generation that develops 
on the leaves and a second generation that settles on the bark and overwinters as adult 
female (Liu et al., 1989). The adult females of C. wistariae exhibit two morphological 
forms, linked to the feeding site, differing in the shape of pygidial lobes: the leaf-infesting 
form and the branch-infesting form. This host-site induced dimorphism is recorded also 
in other diaspidids: the two morphological forms of the same species are so dissimilar 
that, in the past, they were described and considered as separate species until the situa-
tion was clarified (Lupo, 1943; Takahashi, 1953; Takagi, 1961). a detailed account on 
this subject is reported by Liu et al. (1989) and by Takagi (1990). 

a few parasitoids swarmed in laboratory from C. wistariae adult females when 
in Italy (august 28-30, 2010). They have been identified as Encarsia citrina (Craw) 
(aphelinidae), a common solitary endoparasitoid of several armoured scale insects. C. 
wistariae is a new host of the above recorded aphelinid.

The scale insects of Wisteria sp.

according to ScaleNet more than 20 different polyphagous scale insect species 
have been recorded on Wisteria trees, but none of these has proved to be a pest, with the 
exception of Eulecanium excrescens (Ferris) (Fam. Coccidae). This asiatic soft scale, 
which has recorded also in the U.S.a., was first detected in europe, London (UK), in 
2001 and has since spread in south-east england, where outbreaks still occur (Malumphy, 
2005; Salisbury et al., 2010). E. excrescens has also been recorded occasionally on other 
ornamental and fruit trees, but apparently Wisterias are the preferred host. according to 
Malumphy (2005), E. excrescens has one generation/year; the nymphs overwinter and 
reach maturity in april. The adult females lay eggs in May; crawlers emerge in May-June 
and settle on the leaves; in autumn, before the leaves fall, they move from the leaves 
to the twigs to overwinter. Damage consists in sap sucking, excretion of honeydew and 
the development of black sooty mould which reduces the aesthetic value of the plant. 
With regard to C. wistariae, as reported above, no damage to the infested plant has been 
observed; this is in accordance with Miller et al. (2005), who consider that C. wistariae 
is not a pest of Wisterias in the U.S.a., where the scale was introduced more than one 
hundred years ago.

The University Botanical Garden of Cluj Napoca is, so far, the only european 
location where this species has been recorded outdoors; further investigations on old 
Wisterias trees growing outdoors will probably demonstrate a larger distribution of this 
species in europe.

aKNoWLeDGeMeNTS

Many thanks are due to Dr. C. Malumphy (Food and environment research agency, Sand 
Hotton, York, UK) for his valuable and detailed information on Chionaspis wistariae 
interceptions, to Prof. antonio Garonna (University of Naples, Italy) for the parasitoid 
identification and to C. Hodgson (The National Museum of Wales, Cardiff, UK) for 
kindly revising the manuscript.



151G. Pellizzari: First record and establishment of C. wistariae in europe

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giuSePPinA PeLLizzAri - Università di Padova, Dipartimento di agronomia ambientale e Produ-
zioni Vegetali - Viale dell’Università 16, 35020 Legnaro, Italy. e-mail: giuseppina.pellizzari@
unipd.it

accepted 30 November 2010