Chalk Hill Blue (Polyommatus coridon)

Family: Lycaenidae Checklist: 61.020

 
Description
Wing span: 33-40 mm. The Chalk Hill Blue exhibits strong sexual dimorphism, with the males being a pale sky blue, and the females a chocolate brown. The black markings on the male's wings are highly variable. The distribution of this species follows the distribution of Horseshoe Vetch which, in turn, follows the distribution of chalk and limestone grassland. This species is therefore restricted to England, south east of a line from the Wash to the Severn estuary.
 
Images (click to enlarge)
Chalk Hill Blue ♂ © David Hastings
Chalk Hill Blue ♂ underside © David Hastings
Chalk Hill Blue ♀ © David Hastings
Chalk Hill Blue ♀ underside © David Hastings
Male Male underside Female Female underside
 
Life Cycle
There is one brood per year. Adults emerge in the first half of July in typical years, with a peak being reached at the end of July and early August. The ovum is the over-wintering stage.
 
Larval Foodplants
The sole larval food plant is Horseshoe Vetch (Hippocrepis comosa).
 
Nectar Sources
Adults feed primarily on Bird's-foot Trefoil, Field Scabious, Selfheal, Thistles and Thyme.
 
UK Conservation Status
Vulnerable
 
Earliest UTB first sighting (since 2004) : 24th June
Mean UTB first sighting (since 2004) : 5th July
 
Species Champion
Nick Bowles
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Reports
 
Distribution and Sites
 

Key
1 sighting 2-9 max seen 10+ max seen
This species is a habitat specialist. It can be found at these sites:
Berkshire
Lardon Chase
Seven Barrows
Buckinghamshire
Aston Clinton Ragpits
Buttler's Hanging
College Lake
Dancersend
Grangelands
Holtspur Valley
Ivinghoe Beacon
Lodge Hill
Prestwood LNR
Yoesden Bank
Oxfordshire
Aston Rowant NNR
Aston Upthorpe Downs
Hackpen Hill
Hartslock
Watlington Hill

 
Related Species
All Species