This woodland butterfly gets its name from the series of "pearls" that run along the outside edge of the underside of the hindwing. Males are often seen flying swiftly, low across the breeding site in search of a mate and are extremely difficult to follow, the colouring of the wings providing excellent camouflage against the dead bracken that is often found at these sites. The Pearl-bordered Fritillary may fly with the Small Pearl-bordered Fritillary at certain sites, although the Pearl-bordered Fritillary, which emerges a couple of weeks before the Small Pearl-bordered Fritillary, generally appears much paler in colour as a result.
In England and Wales this butterfly in scattered and isolated colonies south-west of a line running between Denbighshire in the north-west to East Kent in the in south-east. There are also colonies in Westmorland and West Lancashire. It is also widespread in central Scotland, but very local or absent in the north and south of the country. In Ireland it is found in the Burren limestones of Clare and South-east Galway. It is absent from the western and northern Isles of Scotland, the Isle of Man and the Channel Islands. This butterfly forms discrete colonies which vary wildly in numbers, from a couple of dozen to over a thousand, this being largely-determined by the availability of suitable habitat. Most colonies contain a few dozen adults.
Subspecies: Boloria euphrosyne euphrosyne
The nominate subspecies was first defined in Linnaeus (1758) as shown here (type locality: Europe and north America). The population in the British Isles is represented by this subspecies.
This is the earliest of our fritillaries to emerge. In good years, the butterfly emerges at the end of April in the south - this butterfly once being known as the "April Fritillary" as a result. Most adults emerge at the start of May, but may not appear until the end of May in more northern sites. In exceptional years, there may be a partial second brood at some southern sites, with adults emerging in August.
Subspecies: Boloria euphrosyne euphrosyne
The chart(s) above have been correlated with the phenology plot below, taken from the UK Butterfly Monitoring Scheme. The blue line gives average counts over the full data set from 1976 to date, and the red line gives the average for the last year.
This butterfly is typically found in deciduous woodland containing open areas, such as woodland clearings, that provide the right conditions, foodplants and nectar sources for this species to thrive. This butterfly can also be found in conifer plantations and limestone pavements in some areas. Sites are generally suitable 2 to 4 years after a woodland clearing has been formed, when the foodplants and nectar sources are optimal for this species. However, these sites can quickly become overgrown and, unless there is suitable habitat nearby, colonies will tend to die out.
Males start their day by nectaring on various flowers, such as those of Bugle, Dandelion, Bird's-foot Trefoil and Buttercup, before patrolling low over the breeding sites in search of a mate, investigating any reddish brown object encountered. When a virgin female is found, the female will fly to a suitable platform, sometimes at some height, where the two mate, staying together for 30 to 60 minutes. Egg-laying females are relatively-easy to follow in flight as they flutter slowly and deliberately low down over vegetation, searching out suitable patches of foodplant on which to lay.
Eggs are generally laid singly on the underside of a leaf of the foodplant, but may be laid on nearby vegetation. The egg is yellow when first laid, turning grey prior to the larva emerging. This stage lasts around 2 weeks.
Larvae feed by day and generally rest in leaf litter, but can also be found, especially after hibernation, basking on dead bracken. Larvae will eat whole leaves, leaving just the stem intact. They will also feed on only the leaf lobes, at the base of the leaf, leaving characteristic feeding damage that can give away the presence of a nearby larva. After moulting for the third time the larva enters hibernation, generally in a dried leaf, emerging in the spring to complete its growth. There are 4 moults in total.
The Pearl-bordered Fritillary and Small Pearl-bordered Fritillary are most easily distinguished by their undersides. Both species have a row of 7 white "pearls" running along the edge of the hindwing (hence their vernacular names). However, the remainder of the underside of the hindwing is quite different. The Pearl-bordered Fritillary exhibits 2 very distinct additional "pearls", whereas the Small Pearl-bordered Fritillary has a mozaic of white, oranges and browns and, as such, has the more colourful underside.
Pearl-bordered Fritillary (left) and Small Pearl-bordered Fritillary (right)
It is much more difficult to distinguish Pearl-bordered Fritillary and Small Pearl-bordered Fritillary based on their uppersides. However, there are two general differences. The first is with regard to the row of chevrons at the edge of the forewings. In the Pearl-bordered Fritillary, these chevrons are often "floating" and not attached to the outer margin, whereas these chevrons are attached to the edge of the forewing in the Small Pearl-bordered Fritillary. The second is with regard to the row of spots found next to these chevrons. In the Pearl-bordered Fritillary, each of these spots is positioned midway between neighbouring markings. In the Small Pearl-bordered Fritillary, the dots are not midway, but distinctly closer to the chevrons.
Pearl-bordered Fritillary (left) and Small Pearl-bordered Fritillary (right)
![Peal-Bordered Fritillary - aberration - Unknown location - Unknown date [REARED] [Mike Mullis]](phpBB/gallery/images/upload/3e2708e222a43c74551b1d6518701f47.jpg "Peal-Bordered Fritillary - aberration - Unknown location - Unknown date [REARED] [Mike Mullis]")
![Pearl-Bordered Fritillary - aberration - Marsland - 08-May-04 [Roger Harding]](phpBB/gallery/images/upload/b9864907ad963a97f4ac73d43bc0a88a.jpg "Pearl-Bordered Fritillary - aberration - Marsland - 08-May-04 [Roger Harding]")
![002 [Bob Eade]](phpBB/gallery/images/upload/02369cb7e578d02eca97413659deb29f.jpg "002 [Bob Eade]")
![003 [Bob Eade]](phpBB/gallery/images/upload/6757b2bcc0d589ae72c29a8e4af266c4.jpg "003 [Bob Eade]")
