Dark Green Fritillary

Photo by Callum Macgregor

Dark Green Fritillary  Speyeria aglaja (Denis & Schiffermüller 1775)  

 Family:  Nymphalidae, subgroup Argynninae (the Fritillaries) 

Name origin

Description

This species is a large butterfly which flies very fast in a swooping pattern, except for females investigating egg-laying sites.

 

The upper side of all four wings are bright orange with a distinctive black pattern and white edges to the wings.  In flight it looks vivid orange.  The closed wing view is unique amongst fritillaries because the hindwing has large silver-white spots on an olive-green ground colour.  Females and males appear similar though females have whiter wing edges.

Male 

Female

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 even coastal dunes (but not in Yorkshire). The main food plant is Common Dog-violet Viola riviniana, but other violet species are also used, including Marsh Violet, V. palustris, on wetter habitats.

 

It can withstand cooler, damper conditions than many other fritillaries and prefers lush, strong-growing violets in a sward around 8 to 15cm across with tree, shrub or bracken growth nearby.  It is a hardy species and can be seen nectaring on thistles on quite bleak moorland, sometimes without any obvious violets nearby.

 

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

Status

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.

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

Status

Butterfly Conservation priority:  Medium (but a regional priority in several England regions)

European status:  Not threatened

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

Catherine Jones                   07/05/21