Dark Green Fritillary

Photo by Callum Macgregor

Dark Green Fritillary  Speyeria aglaja (Denis & Schiffermüller 1775) also Argynnis aglaia

 Family:  Nymphalidae, Genus:  Speyeria ( The Greater Fritillaries) 

Etmology Name origin: Speyeria  come from the 19th century German Lepidopterist Adolph Speyer.  Aglaja  was youngest daughter of Zeus was said to personify charm, beauty and grace 

Identification

Male 

Female

A fast but very graceful swooping flyer and somewhat larger that a comma with whom it is often confused. It flys over meadows and woodland clearing from mid June til end of August at altitude. The darker females  can be seen diving down into teh grasses while investigating egg-laying sites.

 The upper side of all four wings of the male are bright orange with a distinctive black pattern with a white fringe to the wings when very fresh.  In flight it apears vivid orange.  The closed wing view is unique amongst fritillaries because the hindwing has large silver spots on an olive-green ground colour.  Females  are somewhat more variable but generally less golden and stronger marked with black and the outer edge lunules are very often pale, almost white 

ID Tips 

Can appear similar to a Wall or a Comma in flight although  much more graceful swooping flight than either. The silver-washed is more silvery gold in flight and rarely leaves the woodland margins while Dark-green prefers na open habitat and appears  2-3 weeks earlier in mid June 

by Dave Williamson

Habitat

The Dark Green Fritillary uses a range of habitats containing violets, including flower-rich chalk or limestone grasslands, acidic bracken moorland, woodland rides and clearings, and coastal dunes. The main food plant is Hairy Violet on Chalk  elsewhere Common Dog-violet  but also Marsh Violet,  on wet habitats.

 

It can withstand  a cooler climate  if damp than many other fritillaries and prefers lush, strong-growing violets in a  low sward around 8 to 15cm in height with tree, shrub or bracken growth nearby.  

It is quite a wanderer and colony centres can be difficult to identify plus it does have a habit of diappearing from a locality and then reappearing a few years later. It can be seen nectaring on thistles on quite bleak moorland, sometimes without any obvious violets nearby or flying along dry valleys of the wolds when the nearest colony is on the North York moors. At the same time It can be occur in lareg numbers where there is abundnat violet growth.  It seems to prefer  wetter conditions and can recolonise old haunts rapidly in  if wet is combined with warm.  Sensitive to drought

 

Butterflies may congregate to nectar in the early morning and evening, especially where patches of purple flowers like thistles and knapweeds occur.

Status:   Occupancy  has doubled in the last 20 years while Abundance has fallen 40% 

UK Status  Widely distributed  although stroger near the coast. Many colonies  have been lost particulalry  from Eastern counties  due to  habitat loss to farming

Butterfly Conservation priority:  Medium (but a regional priority in several England regions) European status:  Not threatened

Yorkshire used to have 3 species of  large Fritilleries including the High Brown but that species was lost in the cold spell of  the late 19th century  The Dark-green has waxed and waned with warm and cool spells but is one of our most cold tolerant species. In recent warm spell of teh last decade it has seen considerabel spread.

We still have lots to learn about this species and one of the difficulties about studying it is finding it! Most sightings appear to be nowhere near where the butterfly might be breeding, and there are few areas where it can be reliably found from year to year.

 

lt seems likely that the species uses its mobility to travel around quite a large area and butterflies raised on one site may move away to breed on another.  The species can be quite mobile with mark/recapture experiments recording movements up to 5km (Asher et al 2001).  It is thought that some individuals might go further and there may be undiscovered colonies in Yorkshire.

 

On the North Yorkshire Moors its survival appears to depend on a network of small colonies.  The richer clumps of violets it prefers are usually found temporarily then overtaken by other species.  Therefore an ability for the Dark Green Fritillary to move on is essential.

 

The butterfly appears to benefit from widened rides and clearings as well as rotational scrub clearance.  lt may temporarily benefit from clear felling where this produces a flush of violets, but commercial replanting will eventually shade out such sites and make them unsuitable again unless suitable rides and clearings are built into the planning.  On grassland sites overgrazing by rabbits or farm animals can damage violet growth and lead to site unsuitability though light grazing can help.  Winter management projects on sites known to harbour colonies should bear in mind the hibernating larvae hidden away in the leaf litter.


The species isn’t totally widespread.  It is a localised resident and wanderer and is found in the western Pennines (Malham Tarn, Scar Close, Ribblehead area), North Yorks Moors, where there are colonies toward the western edge; e.g. Sutton Bank, Farndale, Dalby Forest, Lockton High Moor and Goathland Moors and the Harrogate area.  There are also colonies near Richmond, Catterick and Leyburn, plus the coastal area including Scarborough.

 

Dark Green Fritillaries became less common in the 1950s and 60s but are becoming more widespread now.

 

Worldwide the species ranges from Morocco and the North Mediterranean coast northward to Norway and eastward through Asia to China and Japan.

When and Where

Life Cycle

The species is single brooded.  Eggs are laid singly on plants or in litter near foodplants and the larvae hatch after two to three weeks, going straight into hibernation in the leaf litter or grass tussocks.  They become active again in the following spring and develop through five instars.  Fully grown, they are dark, almost black, with lines of orange-brown dots along the sides. Pupation usually occurs late May to mid-June (in Yorkshire) and butterflies hatch out three to four weeks later.  Males patrol over large areas in search of females, which tend to hide away in undergrowth where mating takes place.

by Callum Macgregor

Food Plants

Hairy Violet      (Viola hirta)

Usually found in short turf in chalky places. Flowers March to May, pale bluish-violet. Plants without stolons, forming small clumps of discreet plants. Leaves hairy below and on petioles, with hairs spreading or erect, not flat.  Blunt sepals and curved spur on flower.

Aberrations

This is a variable species with almost 100 aberrations described.  Ab albomaculata (Rebel) is an albino form where the black markings are silver-grey and ab charlotta Haworth has silver spots on the base of the underside hindwings that are joined into blocks.

 

Also the amount of green on the underwing can be variable.

With thanks to The Butterflies of Yorkshire edited by Howard M Frost  and  Catherine Jones  07/05/21