The Elm Leaf Hopper Iassus scutellaris (Fieber, 1886) at large in Worcestershire
Gary Farmer
The leaf hopper Iassus lanio will be a familiar insect to anyone who has a mind to shake the branches of oak trees into a net or up-turned brolly. This relatively large leaf hopper (6.5mm to 8.3mm. long) from the family Cicidellidae is wide-spread across Worcestershire and likely to turn up on oak trees almost anywhere in the county (01). However its rarer cousin Iassus scutellaris has become established in the south of the county living in elm hedges.
On 24th July 2014 while surveying hedgerows at Vale Landscape Heritage Trust's reserve Littleton Meadows I found a small Iassus bug and photographed (02) it because “it didn't look right”. I ts wings were more translucent than any I. lanio that I had seen and it was oddly marked. I checked the British Bugs WebSite and found that it strongly resembled I. scutellaris a Nationally Notable A species found on elm. A check of the distribution on NBN Gateway suggested it to be a species restricted to south east England and East Anglia.
A check on the Auchenorrhyncha Recording Scheme WebSite revealed that the species is now more widely distributed and gives the following account:
“Discovered in Surrey in 1978, this species [Iassus scutlellaris] is now found widely across southern and central England despite its classification as Nationally Notable A. Associated with English Elm Ulmus procera and able to persist on low re-growth following dieback due to Dutch elm disease, it is similar in appearance to the common oak-feeding I. lanio but the colour of the forewings is generally a much brighter lime-green.”
I forwarded my record and photograph to Alan Stewart the Auchenorrhynca Recording Scheme Organiser who gave this cautionary reply:
“…..The distinction between Iassus scutellaris and Iassus lanio is a rather subtle one. …... Externally, it is mainly a question of the pointedness of the vertex (top of head), which I can’t really see on the photo. The fact that it was on elm is highly suggestive of I. scutellaris, but not completely reliable unfortunately as I. lanio can sometimes be found on this tree, although its main host is oak. I have a record of scutellaris from SP24 so not that far from where you found yours. I think this is one of those species for which one would need to examine a specimen to be absolutely sure; getting the right angle on a photo to see the necessary features is extremely difficult …... I would be reluctant to add the records to the recording scheme database without someone inspecting a specimen”.
Unfortunately I had not kept a specimen and a return visit to the location failed to turn up any further examples. However I had been given permission to visit the Worcestershire Wildlife Trust reserve of Hill Court Farm and I took the opportunity to beat some of the hedgerows for invertebrates. I collected several individuals of what I believed to be I scutellaris. I photographed (03) some of the bugs to show the variation and kept one as a specimen. This I pinned alongside a specimen of I.lanio for comparison (04). A clear difference can be seen in the vertex of the two species; I. scutellaris appears to have a longer 'nose' because of the shape of the vertex. It is also a smaller insect and in life is a paler more translucent green. The brown markings are variable but distinct from I. lanio. Iassus scutellaris has undoubtedly become established in the county recently but has remained undetected, possibly because of its similarity to its common cousin.
References:
British Bugs WebSite: www.britishbugs.org.uk
Auchenorrhyncha Recording Scheme WebSite: http://www.ledra.co.uk/
Wilson, Michael R. 1981, Identification of European Iassus species (Homoptera: Cicidellidae) with one new species to Britain. Systematic Entomology 6:115-118
Biedermann, R.& Niedringhaus, R. 2009. The Plant- and Leafhoppers of Germany. Identification Keys for all species
Images
01. Iassus lanio Lower Smite Farm 20 July 2014. Gary Farmer
02. Iassus scutellaris 24 July 2014 Littleton Meadows. Gary Farmer
03. Iassus scutellaris 20 August 2014 Hill Court. Gary Farmer
04. Iassus scutellaris (right) & Iassus lanio (left) pinned specimens. Gary Farmer
