|Glanville Fritillary on Red Valerian|
Photo © Ian Pratt
The Glanville Fritillary (Melitaea cinxia) can be found along many stretches of the Island's
southern coastline, especially where the cliffs are slumping and
landslips are annual as this provides the right conditions for
growth of new young plants of Ribwort Plantain (Plantago
lanceolata), on which the female lays her eggs. Colonies
exist primarily on sandstone and clay exposures of the
undercliffs and chines and on the cliff-top grassland above. The
colonies on Mottistone and Compton Downs are on chalk downland.
Please note that the majority of Glanville Fritillary sites are on National Trust
land, where it is illegal to collect any of the life stages.
Collecting is also highly damaging, particularly when
populations are at a low ebb.
Look for Glanvilles during warm, sunny
weather, with no more than light winds (adults hide in the grass
on dull, windy days). Search for butterflies where there is a
good supply of flowers for nectar. Thrift (Armeria maritima),
corniculatus), Kidney Vetch (Anthyllis vulneraria)
and Red Valerian (Centranthus ruber) are favourites and
adults can be closely approached when feeding. Flight is fast
with whirring wingbeats followed by graceful glides low over the
vegetation. Males are quite conspicuous as they patrol in search
of females, which spend long periods resting in the grass.
Mating occurs around midday. The female lays batches of eggs on
the underside of leaves of Ribwort Plantain. She selects small,
young plants growing in abundance in open, sunny ground as such
conditions provide the warmest microclimate.
|Larval web on Ribwort Plantain|
Photo © Peter Hunt
The caterpillars emerge from hibernation
in mid-March, or as early as mid-February in mild springs. They
feed communally in a silken web spun over the foodplant and are
black with spiny black body hairs, tiny white spots and a
rusty-red head. As they grow, they become extremely conspicuous
and can be seen basking on the outside of the web. By late
April, many larvae are fully grown (25 mm long) and disperse,
when they can be seen crossing cliff-top paths.
|Larvae on Ribwort Plantain|
Photo © Peter Hunt
Populations undergo cyclical
fluctuations. A poor year may be due to unfavourable weather, a
high rate of larval parasitism, lack of foodplant causing larvae
to starve to death, or any combination of these. Numbers will
gradually build up again after a crash and cycles last five or
six years. There are thought to be 5-8 core colonies, which hold
permanent populations and at which several hundred butterflies
can be seen in a good year. During bumper years, Glanvilles form
transient colonies elsewhere along the southern coastline and
further inland, even reaching the northern coastline.
In a 'normal' year, Glanvilles are usually on the wing at most
sites by 20th May and the peak flight period is the last week of
May and the first week in June. At the end of the peak, numbers
usually decline fairly rapidly but Glanvilles may be seen
throughout the month and sometimes into July. However, emergence
depends on the onset of spring and if spring is early and warm,
the first adults will fly at the beginning of May or even in
late April and the flight period may then be virtually over by
the end of May/early June. Prolonged poor weather in June is
likely to curtail the season. Note than Glanvilles inhabiting
the sheltered, southeast-facing Ventnor coastline may emerge two
or three weeks earlier than at other sites and are more
frequently seen in early May.
|Glanville Fritillary on Thrift|
Photo © Elaine Rice
Flight periods on the Isle of Wight, 2006-2010
2006 14th May to 3rd July (both Wheelers Bay)
2007 8th April** (Bonchurch to 9th June (Brook Chine)
2008 2nd May to 23rd June (both Wheelers Bay)
2009 25th April to 27th June (both Wheelers Bay)
2010 1st May (Wheelers Bay) to 25th June (Compton Chine)
** this is an exceptionally early date and followed a mild
winter and a very warm start to April.
Glanville Fritillary Sites
East Wight - Wheelers Bay to Horseshoe Bay
Usually the site where the first Glanvilles are seen each year
due to its sheltered, southeasterly aspect. The flight period is
also long here, with the first and last individuals coming from
this site in many years.
Eastern Esplanade car park (east of
Oceanblue Quay), SZ 565 773, is the nearest. Parking also
available in Ventnor town centre and at Shore Road, Bonchurch.
No. 3 route from Ryde to Ventnor and Newport to Ventnor.
Wheelers Bay and Horseshoe Bay are reached by heading east along
the seawall from Oceanblue Quay. Glanville Fritillaries can be
seen from the seawall, flying around the vegetation on the
sloping banks and on and at the base of the cliffs.
Dingy Skipper, Clouded Yellow, Common Blue; Cream-spot Tiger; Wall Lizard.
Photo © Peter Hunt
West Wight - Compton Bay/Shippards Chine
From the mainland. Easiest route if coming for the day without a car is via the
Lymington to Yarmouth ferry, then the No. 7 bus to Freshwater,
change at Freshwater and get the No. 12 bus to the Hanover Point
bus stop next to the National Trust car park. Alternatively,
catch the open-top Needles Breezer bus from Yarmouth to
Freshwater Bay and either catch the No. 12 bus from here or walk
along the cliffs to Compton Bay and Shippards Chine. Note that
there is a taxi rank outside the Yarmouth ferry terminal.
Ice-cream van and toilets at the Hanover Point car park.
From the Hanover Point car park, head west along the cliff-top
path. Glanville Fritillaries can be seen anywhere here.
Especially check the areas with Thrift.
A profitable route is to continue west along the cliff path
until reaching the A3055 Military Road at SZ365854. Turn
right/east and walk alongside the road for 150 m until you see a
small car park in an old chalk quarry on the opposite side of
the road (at SZ367854). This is one of the best sites on the
Island for butterflies. Grizzled and Dingy Skippers, Green
Hairstreak, Small Blue, Adonis Blue (on the slopes just above
the quarry) and Wall can be seen here. (Beware Brown-tail Moth
caterpillars, which can give you a nasty rash if they come into
contact with your skin!) The nearest bus stop to this small car
park is at Compton Farm.
Small Copper, Common Blue, Wood
Tiger moth; Bee and Pyramidal Orchids, Hoary Stock.
At Freshwater Bay: Freshwater Bay
Tearooms, the Holiday Fellowship Hotel cafe (stunning views),
Dimbola Museum and Galleries tea room (home of the 19th-century
photographer Julia Margaret Cameron), the Albion Hotel bar and
restaurant, Sandpipers Hotel restaurant and Fat Cat bar.
Brook Green, Sud Moor, Chilton Chine to Marsh Chine
This is an excellent stretch of coastline for seeing Glanvilles.
National Trust car park at Brook Green (SZ385836) and car park
at Chilton Chine (SZ409822). The No. 12 bus goes to Brook Green
but there is no bus to Chilton Chine or Marsh Chine.
Tea room and toilets at Isle of Wight Pearl just east of Chilton
Other IOW specialities
Red Squirrels at Fort Victoria Country Park (
http://www.fortvictoria.co.uk ) between Yarmouth and
Freshwater on the A3054. Can be seen in the woods at the country
park and on the bird feeders outside the Model Railway building.
Ranger's office with information leaflets.
The Ventnor Wall Lizard colony is the oldest and largest in
Britain. Documentary evidence is lacking but it may date from an
introduction in 1841. The colony has now spread into Wheelers
Bay. The lizards live in the cracks and crevices in walls. Look
for it in sunny spots on logs or walls. Special ‘Wall Lizard
walls' have been constructed for them in La Falaise car park and
at Ventnor Botanic Garden.
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