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Rhopalomyia (Hormomyia) ptarmicae (Vallot, 1849) (Diptera: Cecidomyiidae)
Rediscovered in Essex
JERRY BOWDREY
Colchester Museums, 14 Ryegate Road, Colchester COl 1YG
In 1884 W. Cole and J. English found some galled flower heads of Sneezewort Achillea ptarmica growing
near Purlieu Banks, Epping. They sent some examples to Edward Fitch who determined them as
Hormomyia ptarmicae, a species new to Essex. On 24.V.1887 Reginald Christy found more galls at
Loughton (Fitch 1887). On checking his own records, Fitch discovered that he had taken the gall at
Rayleigh in 1873 or 1874, but had omitted the record from his account of Essex galls (Fitch 1882).
Over a hundred years later, in 1996,1 was talking on the subject of galls to members of the Basildon
Natural History Society when Peter Furze mentioned that he had seen some unusual galls on
Sneezewort, at Flax Field, near Basildon (TQ6887). The possibility of R. ptarmicae came to mind;
I was not aware of any records this century. Sneezewort being itself a rare plant in Essex, so I asked
if a specimen could be obtained. However, it was not until 1999 that any galls were refound and the
identification confirmed.
The whole flower head of the Sneezewort is deformed into a compact, wooly mass (see Fig 1.),
covered in a short pubescence and surrounded by deformed leaves. In some cases the gall has a
pinkish hue. I have since searched the few Sneezewort plants in the neighbourhood of Colchester,
but without success. 1 would be interested to hear from anyone who finds other localities for this
interesting gall.
Rhopalomyia ptarmicae on flower-head of Sneeze-wort (from Essex Naturalist 1:177)
References
FITCH, E.A. (1882) The galls of Essex: a contribution to a list of the insect fauna of the County. Trans.
Epping Forest and County of Essex Naturalists' Field Club 2: 98-156.
FITCH, E.A. (1887) Two new Essex gall makers. Essex Naturalist 1: 177-179.
Essex Naturalist (New Series) 17 (2000)