Cream-bordered Green Pea - Earias
clorana (Linn.) A Personal Account of its Occurrence in Cornwall.
Do you ever get the feeling you should be putting the moth trap out (because
the weather is so good) but you're busy doing something else or its time
for bed? In my case, the thought is often in the back of my mind that
I will have to get up at five the next morning to cover the trap before
the moths wake up and fly away or the birds get them... they soon learn
don't they! So it was on the evening of the 26th July this year, after
a spell of warm muggy weather spreading up from the south, my daughter
Abigail reminded me that it was a good night for mothing and could we
go out somewhere with the portable generator. I had to visit a friend
first, so I piled the equipment in the boot and set off to Par before
going onto St. Andrew's Pond for the mothing session.
After fussing around trying to find a good spot, all was set up and ready
to go. About ten minutes after the mercury vapour light was lit, my daughter
asked what the small green moth was found sitting on the lamp flex and
a similar one right beside it. "Tortrix Viridana," came
my rather curt reply. "Err... no it's not," I said, correcting
myself … "Quick, grab a pot," I shouted excitedly…
The next day I 'phoned Mark Tunmore but he was on holiday. I had to wait
a week before he very kindly answered my 'phone message. I explained that
I had found another breeding colony of the Cream-bordered Green Pea Earias
clorana (Linn.) at Par Pond. He rather deflated me with his reply...
"O yes, it's found in several places along the southern fringes of
Cornwall. I've had it on the Lizard a few times. I'm sure it's breeding
there," came his rather nonchalant reply.
In case you are wondering what all the fuss is about and why I was so
excited with the find, the answer goes way back to 1992. In those days
Bill Kittle, my family and I, often visited Carlyon Bay (Crinnis Beach)
to do a spot of trapping in case a few migrants turned up as they often
did. It became a favourite spot simply because of the varied habitat and
therefore the moths that are found there. (Spalding, A. The Moths at
Carlyon Bay, Cornwall Recorded 1989-1993. British Journal of Entomology
& Natural History vol. 8 1995 refers). Unfortunately the owners
of the beach in recent years, have used the woodland to the rear as a
camping area for several WOMAD music festivals and the repeated presence
of thousands of people have in my opinion, somewhat spoiled the natural
beauty of this site along with its flora and fauna. The site owners had
extensively sprayed the area with herbicide and some areas had crucially
been cleared of herbage where it is suspected E. clorana was breeding.
To come back to the point, on the night of Saturday 13th June 1992 the
weather was warm and close. There was no significant migrant activity
apart from a solitary Pearly Underwing - Peridroma saucia (Hüb.)
so to Bill Kittle's surprise, a small green moth seen on the sheet was
identified almost immediately by him as Earias clorana, (Cream-bordered
Green Pea) - a first for Cornwall. It was ab. flavimargo de Joannis,
1908 which has a rather yellowish termen. The specimen was exhibited in
the British Entomological & Natural History Society's Annual Exhibition
1992 and erroneously described as Earias insulana - the Egyptian
Bollworm - an extremely rare migrant/importation from Egypt where it is
a serious pest on cotton. The forewings are similar to E.clorana ab.
Flavimargo in colour having a yellowish apple-green appearance, however
the wings are longer and narrower than E. clorana giving insulana
a completely different look. An excellent description of the genus EARIAS
(Hüb) by B. Goater can be found in the Entomologist's Record
and Journal of Variation vol.106, Nos. 11 & 12, Nov/Dec.1994.
Unfortunately the misidentification has been repeated since, thus compounding
the error. The matter was finally corrected by J. D. Bradley in his Checklist
of Lepidoptera Recorded from the British Isles 2nd edition (revised 2000)
Comments on the 1998 edition by A. Spalding (Atropos vol.6
p.74).
Well, if you have been patient enough to wade through the history of
the occurrence of the moth in Cornwall and its misidentification, I'll
come to the point. The moth has no doubt established itself by immigration
probably dating from 1992 since ab. flavimargo is not known from
native populations (Martin Honey personal comment). Hence the specimen
found at mvl at Carlyon Bay was probably one of the first few specimens
to arrive from abroad (possibly Brittany where ab. Flavimargo is known
to occur) and from subsequent records in the ensuing years, it is assumed
that it began to breed here. It occurred again on the 27th July 1996,
when two came to light and the first indications of breeding were mooted.
However close inspection of the flora at Carlyon Bay did not reveal its
preferred food plant - Creeping Willow - Salix repens and Osier-
Salix viminalis. Other species of willow are mentioned as a food
plant but in my opinion, the caterpillar is simply feeding on Goat Willow
(Sallow) - Salix caprea. A close inspection of the sallows in the
vicinity of St. Andrews Pond, Par during this August may reveal the presence
of the caterpillar during its final instar to confirm a newly established
colony there. Other dates the moth has been found at Carlyon Bay are:
2nd August 1996 - a single specimen, 16th -18th July 1997 when ten were
recorded and 23rd July 1997 when two were recorded. The late dates imply
a second generation.
Finally, from the female taken at St. Andrew's Pond, Par, eggs were obtained
which were laid singly after four days captivity. Although Weeping Willow
was present in the breeding cage, the moth preferred laying on the rough
surface of some tissue wipes placed in the breeding cage. The colour rendering
in the two photographs is not entirely accurate, the eggs having a browner
appearance than the photos imply with a blacker concentric ring. The spherical
eggs some 0.3mm in diameter, after turning a darker colour, failed to
hatch after 17 days and I am inclined to think they are infertile or will
not now hatch due to unknown adverse conditions. I would greatly welcome
some advice on this matter.
I leave you with some photographs of the eggs and adult.
Earias clorana (Linn.) St. Andrew's Pond, Par,
Cornwall. 26th July 2002 at mvl. Photo: P.H.Boggis.
E. clorana ovum laid singly on
kitchen paper in breeding cage.
Ovum: 0.3mm diameter.
30th July 2002.
E. clorana ovum laid singly
on
kitchen paper in breeding cage.
Ovum: 0.3mm diameter.
30th July 2002.
Phil Boggis
(Assistant County Recorder).
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