Unaspis euonymi (a scale insect) – A New Find For Merseyside

On the 4th December 2019, Susan Marley and I visited Stanley Park, Liverpool to record for the Greenspace Challenge project running under the Year of the Environment initiative. One of the plants found in the park was the non-native shrub Evergreen Spindle (Euonymus japonicus). Close inspection of the plant revealed a large number of tiny white scale insects (order = Hemiptera) which turned out to be Euonymus Scale (Unaspis euonymi) (Figure 1), a sap-sucking diaspidid native to South East Asia.

Figure 1. U. euonymi on Evergreen Spindle by the lake at Stanley Park Liverpool 4th December 2019. (c) Steve McWilliam


On the 11th December 2019, Susan Marley and I visited Newsham Park, Liverpool for further recording for the Greenspace Challenge project. Again, a plant of Evergreen Spindle was found and again it was covered in the U. euonymi (Figure 2).

Figure 2. U. euonymi at Newsham Park on 11th December 2019. These insects have soft flattened bodies covered by a shell / scale. Male and females differ in appearance. The males are mainly on the foliage and are covered with narrow white elongate scales that are 2mm long. The females mainly occur on the stems and are covered with blackish brown pear-shaped scales up to 3mm long. The species overwinters as a fertilised female and has one generation per year in the north, and three or four in the south. In early spring, eggs are laid underneath the protective scale, and hatch in May and June. The young migrate by crawling to leaves to feed or may also be blown by the wind to other susceptible hostplants. (c) Steve McWilliam


NBN Atlas features just one occurrence for U. euonymi, from Belgrave in Leicestershire but a map published by the Royal Horticultural Society from the results of their own 2012 survey show the species to be quite widespread in England, north to Yorkshire, having expanded in range since 1950s (Figure 3). These two resources indicate that the species had not been recorded in Merseyside or in South Lancashire previously.

Figure 3. U. euonymi records collated by a 2012 RHS survey.

In the UK, U. euonymi has only been recorded infesting the stems and foliage of Euonymus. Outside the UK, U. euonymi has also been recorded on other hosts including Boxwood (Buxus), Bittersweet (Celastrus scandens), English Ivy (Hedera helix), Holly (Ilex), Privet (Ligustrum), Honeysuckle (Lonicera), Paxistima canbyi, and Pachysandra terminalis.

I would recommend recorders check all/any Evergreen Euonymus plants for this species to better understand it’s status and distribution in our area.

More info:

Liverpool City Region Year of the Environment 2019

Liverpool City Region Greenspace Challenge