summer plants of the upper meadows include Greater
Knapweed, Hardheads (=Lesser Knapweed),
Scabious, Meadow Cranesbill, Alexanders,
Meadow Vetchling, Yarrow,
St. John's Wort*, Great Mullein* and many
others. Herb Robert is
found amongst the scrub.
(*notably on disturbed ground.)
Plants of Ancient Downland
indicators on the lower slopes include Dropwort,
Ladies Tresses (upper plateau), Hairy
of which are rarely found on pastures, restored wildlife meadows or agricultural
downland. Other downland plants that are more likely on the biodiverse
down herbland are Wild Thyme,
Thistle, Dwarf Thistle, Squinancywort,
Flax, Small Scabious,
Basil. There are other more widespread
wild plants like the Mouse-eared Hawkweed,
Rough Hawkbit, Lesser Hawkbit, Bird's Foot Trefoil, Ground
Speedwell, Field Speedwell, Sweet Violet,
and Yellow Wort.
Wild Flora and Fauna on Chalk flickr
Adur Wild Flowers 2009
A large part (724 acres) of the downs including Mill Hill were presented to the people of Shoreham in 1937.Local Nature Reserve. This is divided into about 11 acres of grassland and meadows above the ridge, about 9 acres of scrub, the copse and glades at the northern end, and about half of the prime Chalkhill Blue area of 6.4 acres of herbland remaining. 6 acres has been lost to a Sycamore woodland on the southern slopes.
This is low fertility chalkland not suitable for grazing. The top area is effectively a wild meadow and the lower slopes a rabbit warren dominated by prostrate (not the upright form) Horseshoe Vetch, Hippocrepis comosa.
Hill is nationally important because of its population of Chalkhill
Blue Butterflies. Estimates of the numbers
are notoriously inaccurate. In the 1950s
the population was estimated by R. M. Craske
be 50,000. This may be an exceptionally good year. I would estimate the
numbers at that time to be nearer 25,000 for Mill Hill only. After the
cattle grazing and thorn incursions the numbers plummeted to the most reliable
estimate in 1960
of 6,000. The new road and Sycamore woodland further denuded the Horseshoe
Vetch, Hippocrepis comosa,
and bare chalk downland to a figure I have estimated at a top figure of
3,000 Chalkhill Blue Butterflies at the turn of the millennium (counted
in 2003). Almost
all these butterflies are now to be found on the six acres of the lower
family lived at The Mill House, Mill Hill, from around 1933
until about 1967, and every July we saw the
"Butterfly Men" walking past onto the Downs. My father used to tell
us that they were interested in the blue butterflies."
Heather Clark (née Eager), Ryde, Isle of Wight
Postcode: BN43 5FH
Grid Ref: TQ 21170 07444 (upper car park)
Geographic Link OS Map
Google Earth Map
Magic Map of Mill Hill NR
Local Nature Reserve Designation
Natural England: Local Nature Reserves
Multi-Map (Bird's Eye View)
Grid Reference Finder
The butterfly lower slopes at Mill Hill are under serious threat by a natural process known as ecological succession where the woody shrubs like Privet, Brambles and Hawthorn invade the herb-rich slopes gradually turning the downs into woodland and eliminating the butterfly larval food plants especially the Horseshoe Vetch, Hippocrepis comosa, on which the Chalkhill Blue Butterflies rely. The remedy is by expert professional removal of the Privet on a regular basis. This job is now being undertaken by volunteers.
at Mill Hill
30 May 2019
Belle Moth, Aspitates
Tatty Adonis Blue with Horseshoe Vetch seed pods
a Fresh Breeze
afternoon, about forty Adonis
around the lower slopes of Mill Hill, with a few male Common
Blues, with occasional Brimstone
Butterflies on patrol, frequent 20+ Small
Heaths, a Cinnabar
Moth, and a Yellow
Belle Moth, Aspitates
ochrearia. Some of the
Blues were as tatty as the fading Horseshoe
were searched out. There was a Speckled
Wood amongst the scrub. On the top of
the hill, the first Greater Knapweed
was in flower.
Adur Moths 2019
rarely allowed to grow into a small tree. Interesting
fact: in the sun the twigs are coloured crimson, while those in the shade
are lime green.
Woodland Trust Information
21 May 2019
White fluffy Cumulus clouds allowed intermittent sunshine brought frequent butterflies out on the lower slopes of Mill Hill. About three quarters were lively Adonis Blues (38+7=45 in the transect acre, more over the slopes) over the swathes of Horseshoe Vetch, Hippocrepis comosa, frequent Small Heaths (20+), patrolling Brimstone Butterflies (10+), a few Large Whites, a fresh Grizzled Skipper, a fresh Dingy Skipper, a Wall Brown (on the southern steps), a very fast flying Peacock Butterfly, at least two each of Burnet Companion Moths, Cinnabar Moths and Treble-bar Moths. Two pairs of Adonis Blues were mating. Grasshoppers were stridulating at the northern end of the lower slopes and small movements were thought to be nymphs. Wild Mignonette was in flower. The first Dropwort appeared on its tall stalk above the short green vegetation.
Mignonette, Dropwort, Hounds-tongue
Horseshoe Vetch & Milkwort, Bladder Campion
I noted the meadow north of the upper car park was now covered in Brambles and the vegetation already up to chest height. I did not venture in as it was getting late in the afternoon. The middle slopes immediately south of the Copse had patches of Horseshoe Vetch and the first Bladder Campion was just about flowering. Crosswort was recorded for the first time (it is easily overlooked) on Mill Hill. Hawthorn was beginning to lose its blossom as Elderflower was beginning.
Rain curtailed my early afternoon visit, on a day not bright enough to make the butterflies active, although I disturbed five male Adonis Blues, one Brimstone Butterfly, and a Cinnabar Moth in a leisurely fifteen minute of less than half the one acre transect on the lower slopes.
Hairy Violet, Bulbous Buttercup
I noted the following wild flowers for the first time this year: Rough Hawkbit, Mouse-eared Hawkweed, Hairy Violet, Dog Rose and the first flowering on Mill Hill of the large shrubby Hounds-tongue. The smaller than usual amount of flowering Horseshoe Vetch, Hippocrepis comosa, was disappointing, with none around the Tor Grass, which appears to have spread.
13 May 2019
Blue, Treble-bar Moth, Adonis
Brown Argus, Speckled Wood, Adonis Blue
Adonis Blue, Adonis Blue. Dingy Skipper
a sunny afternoon on the lower slopes of Mill Hill produced scores of restless
fluttering around the early swathes of Horseshoe
Vetch, Hippocrepis comosa,
There were well over a hundred per acre of nine
species and all of them were very active and
I had to wait for over an hour for any to settle nearby. Dingy
Skippers were the most frequent with over
forty seen, but Grizzled Skippers
were old and much harder to find only a handful including an amorous or
sparring pair. The only one that settled for a second was slightly frayed
at the edges. Twenty or so male
Blues were very lively until they came
across a few females.
Heaths (12+) were frequently seen often
chasing each other and sparring with other species including occasional
Butterflies patrolled incessantly without
pausing, occasionally bumping into the whiter females and both a Large
White and a Green-veined
White. A flash of grey was a disturbed
Moth, and a pretty Mother
Shipton Moth was recognised when it settled.
A Speckled Wood patrolled
the southern steps and a fresh Brown Argus
seen clearly by the winding path, near some Wayfaring
Nine butterfly species and two macro moths
Hawthorn was flowering all over Mill Hill on some small trees at its peak blossom. On the top, south of the reservoir, the thick stems of Knapweed Broomrape appeared. This is a large parasitic plant. Nearby, the Cowslip patch was nearing the end of its flowering period. I also noted some Bird's Foot Trefoil with its small yellow flowers. On the lower slopes there were Dog Violets and clumps of Milkwort amongst the Horseshoe Vetch.
2 May 2019
Dingy Skipper with Horseshoe Vetch, Hippocrepis comosa
of brilliant blue over the lower slopes of Mill Hill heralded the beginning
of summer on the downs with the first male
Blue Butterfly of the year. It was unmistakable
even though seen in the middle distance for 15 seconds at most; too far
away to follow it for a photograph. Under
a dark cloudy sky with the first spots of rain,
it was too cool for many butterflies.
It was only after nearly an hour did I manage to disturb the first of half
a dozen Dingy Skippers,
followed soon after by a Small Heath,
a Green-veined White
and a probable Peacock Butterfly.
If I had not delayed my return I would missed the Adonis
Blue and a probable Wall
Brown. A Cinnabar
Moth was seen clearly but it quickly disappeared
into shelter. Crane-flies
were mating. And the green beetle on Bulbous
Buttercup seems to be Cryptocephalus
aureolus. The small green grasshopper
nymphs frequently seen on the lower slopes of Mill Hill were probably the
Green Grasshopper, Omocestus viridulus. A small Holly Tree
appeared amongst the undergrowth on the disturbed ground.
24 April 2019
Vetch, Cowslips, Milkwort,
Dog Violets, Hawthorn, Dandelion
did not show on
the lower slopes of Mill Hill, with a chill
(air temperature 12° C) on the breeze (Force
6 gusting to Gale Force 7) and intermittent April showers. A
Wood made a flight near the southern steps,
at the last knockings, as I headed for home
in light rain. Wayfaring Tree was
beginning to flower.
Ant, Myrmica sabuleti
With the first Horseshoe Vetch, Hippocrepis comosa, appearing in bud on the lower slopes of Mill Hill, more butterflies were seen than expected on as hazy afternoon (air temperature 16° C).
of ten butterfly species was more apparent
than sheer numbers with Speckled Wood
(one on the southern steps), Brimstone
3+, Small White
1+, the first of the year Small Tortoiseshell
(southern, top), the first of the year pair of Dingy
Skippers, 2+ Grizzled
Skippers, 1+ male Orange
Tips, another first of the year fresh
Copper, at least one Peacock
Butterfly, occasional Small
Heaths 4+, and two Treble-bar
Moths. Micro moths
were frequently seen and ones recognised were the pyralids
Pyrausta purpuralis and
despicata as well as an even smaller
A small bee
was occasionally seen, small and rather distinctive in yellow and black
barring: I think this was a Nomada
species, most likely Nomada goodeniana.
Very small bright green grasshopper nymphs
were seen amongst the dense green undergrowth.
Adur Butterfly List 2019
There was one large (25 cm with a truncated tail) Slow Worm, south of the Reservoir.
Plenty of butterflies out in the warm sun on Mill Hill this afternoon: at least five male Orange Tips, loads of Brimstone and Peacock, couple of Small Tortoiseshell and a single Green Veined White. Possible Grizzled Skipper but only a fleeting glimpse. Bird wise, Whitethroats and Blackcaps were there, along with the Chiff Chaffs. A few Swallows were passing through.
17 April 2019
I disturbed a single Skylark from the plateau of Mill Hill on a hazy afternoon. It took flight after I thought I heard it singing earlier, but there were House Sparrows (? ID) singing melodiously for a mate from the scrub, and it was too hazy to see a lark in the blue sky. Cowslips were flowering by some rabbit burrows (disused) on the middle open part of Mill Hill west of the top copse.
Spikenard (dead), Speckled Wood
Grizzled Skipper, Milkwort with Pill Bug
the middle of the lower slopes I spotted just a single Grizzled
Skipper, followed by the small pyralid
Pyrausta nigrata, and later a Small
White Butterfly and a strong flying Peacock
Butterfly, and on my return journey a
Wood fluttered around the southern steps.
Violets were now abundant but there still
seemed to be less scattered over the slopes than in previous years. Milkwort
were poking out of the short vegetation.
I noted the top leaves were much longer than the leaves at the rosette
base. This is typical of the local Milkworts
which I have identified as Common Milkwort
vulgaris in previous years, but this
has not been confirmed. Occasional spiders
were spotted crawling rapidly over the undergrowth, mostly very small Wolf
Spiders, Pardosa, but also a full
sized Nursery Spider
and a tiny pale Crab Spider.
On a afternoon when the sun came out unexpectedly, I quickly spotted my first two Grizzled Skippers of the year on the lower slopes of Mill Hill, now decorated with Dog Violets, but much more sparsely than normal. A Common Bee-fly hovered above the violets and a Carder Bee flitted between the flowers quicker than my camera could focus. My first Brimstone Butterfly of the year fluttered past. The first of three Peacock Butterflies landed intermittently. No more skippers were seen.
Adur Butterfly List 2019
the Adonis Blue
Butterfly* with attendant Red
(*these could be a Chalkhill Blue caterpillars)
Most of the observed action occurred amongst the dense interlocking leaves on the lower slopes where a brigade of working mutualistic red ants, Myrmica sabuleti, were attracted by sugary secretions of the green and yellow caterpillars of the Adonis Blue Butterfly. The ants are meant to protect the caterpillars (some were fourth instar) and pupa from predation. Ben Greenway helped me find the caterpillars, but I found one for myself by following the ants activity.
larvae are green with yellow stripes running along the length of the body.
Unlike its close relative, the Chalkhill Blue,
the larva of the Adonis Blue
feeds by day. The larva has a Newcomer's gland in the 7th segment which
provides secretions that are attractive to ants. This is a symbiotic relationship
for, like many other blues, the Adonis Blue larva (and pupa) is afforded
protection by the ants from parasites and other predators.
Early instars feed by grazing on one side of the leaf, leaving the epidermis of the other side intact. When not feeding, the larva rests at the base of the food plant, often on bare soil. Ants are known to bury the larva in a cell in the earth, where the ants continue to "milk" it for secretions. If not over wintering, this stage lasts around a month."
The primary larval food plant is Horseshoe Vetch, Hippocrepis comosa.
Adonis Blue Life Cycle (UK Butterflies)
A small Wolf Spider, Pardosa, crawled amongst the undergrowth. The upright dead bronze and silver dead Carline Thistle plants were quite noticeable on the lower slopes, as expected.
Amongst the scrub on the upper part of Mill Hill, the white blossom of Blackthorn looked attractive against the blue sky. There were a few Cowslips south of the Reservoir (the only upper part of Mill Hill visited.)
I stopped in at Mill Hill and managed to find a Grizzled Skipper, the first of the year reported in Sussex.
19 March 2019
Wind-blown Hawthorn above the Ridge
a dull afternoon I made my first cursory visit of the year (after
a week of squalls) to Mill Hill, just to the
area around the Reservoir. A hundred mixed
filled the cloudy sky. There were Sweet
Violets scattered sparsely over the undulating
area immediately south of the Reservoir. Clumps of Daffodils
were still showing. Even the small birds flying between the bare branches
were hard to discern as it was so dark. Some of the paths were muddy but
there was no standing water seen.
Mill Hill Wildlife Reports 2018 (Link)
Hill Wildlife Reports 2016 (Link)
Mill Hill Wildlife Reports 2015 (Link)
Mill Hill Wildlife Reports 2014 (Link)
Mill Hill Wildlife Reports 2013 (Link)
Mill Hill Wildlife Reports 2012 (Link)
Mill Hill Wildlife Reports 2011 (Link)
of Grasses (Link)
Mill Hill Grasses
Reserve is defined in Section 15 of
the National Parks and Access to the Countryside Act 1949,
as land managed for the purpose:
of providing, under suitable conditions and control, special opportunities
for the study of, and research into, matters relating to the flora and
fauna of Great Britain and the physical conditions in which they live,
and for the study of geological and physiographical features of special
interest in the area; or
SPECIES OF BUTTERFLIES DEPENDENT ON MILL HILL
(Estimated numbers for Mill Hill Nature Reserve only are in brackets)
Blue (3000 +)
Adonis Blue (50 -100)
Dingy Skipper (75)
Wall Brown (12)
Meadow Brown (300)
|Marbled White (50)
Speckled Wood (>50)
Green-veined White (2+)
Small Blue (5)
Large Skipper (10+)
Grizzled Skipper (20)
Brown Argus (>30)
Green Hairstreak ( a few)
The other species may breed on Mill Hill, but there main breeding area will be adjoining fields or slightly further away. e.g. Small Blue (included above), Small Copper, Small Tortoiseshell, Green-veined White, Peacock, Ringlet, Small White, Large White, Comma, Holly Blue, Orange Tip. (=10). There are huge variances each year for most species.
The following are immigrants &/or hibernators: Red Admiral, Painted Lady, Clouded Yellow.
The following have not been positively identified (because of ID difficulties): Essex Skipper. This species is now included for a local field on the Adur Levels within 500 metres of Mill Hill.
following was confirmed only in 2009:
following was confirmed only in 2014: Dark
The next one is no longer
found on Mill Hill but were there in the distant (1947) past: Grayling.
The next one has been recorded near Mill Hill in the middle distance past: White-letter Hairstreak
Skipper does not appear to ever have occurred
on Mill Hill
The Silver-studded Blue has never been recorded from Mill Hill
The Short-tailed Blue was recorded as a single immigrant in 1956.
A possible (unconfirmed) Brown Hairstreak Butterfly was spotted. A confirmed one was spotted nearby.
Brown Hairstreak and Silver-spotted Skipper have been confirmed from Mill Hill. The first is notoriously difficult to spot and was probably already there. The skipper may be a new addition, but it is small and not easy to spot, and there have now been numerous sightings
History of Mill Hill
Lower Adur Levels (MultiMap) including Lancing Clump and Mill Hill
Vetch, Hippocrepis comosa
First Draft of the Article for the Shoreham Society Newsletter