The Silver-washed Fritillary, Argynnis paphia
This is by far the largest of the UK’s woodland fritillaries, and most people would agree the most spectacular. It is the only Fritillary generally found in Hadlow parish.
This is a female, without the four dark lines of the male on the upperside of the wing, and with an overall darker appearance on the wings:
Here is another individual by “The Triangle” in Dene Park. This one looks a little more worn at the edges than the female above, with a small nibble out of the left wing. Also I eventually worked out that this was a male, from the sex-brands. I think at least the second sex-brand away from its body has burst open (the white line), as designed for showering a female with scented scales, and thus indicates this insect’s prior (hopefully successful) sexual activity.
The photo also shows the greenish and brownish iridescent hairs over the top surface of the thorax that are characteristic of the species.
This is a photo of an adult male in Tudeley Woods middle of July 2014 very clearly showing the male sex-brands, packed with androconial scales designed to release the male pheromone, in the four dark lines on the fore wing only found in the males. The female lacks these four lines, but their black wing splodges tend to be more extensive, thereby appearing darker overall. Femalesy tend to be seen slightly less than the males, and rather later in the season. The photo also shows again the greenish and brownish iridescent hairs over the top surface of the thorax. Its left wing of this individual has in fact been partly severed, perhaps by the bite of a large beak.
This picture below shows the silver streaks and the slight greenish wash on the underside of the hind-wings near the body. This male is feeding off hogweed flowers on the Knights Park path.
The Silver-Washed Fritillary is generally found along woodland tracks in clearings and on woodland edges, and the best place to see it in Hadlow Parish is undoubtedly Dene Park, which is apparently open enough for it, and where the rides are fully accessible to the public. It has also been seen along the edges of Clearhedges Wood. It does tolerate more shade than the other fritillaries, none of which are found in Hadlow. It occasionally wanders a little further afield, but rarely, and to little long-term effect. In Kent it may be found in other woodlands across the county, and currently seems to have a bit of a stronghold around Tonbridge and Hildenborough. This is a rather nice view of a male in Dene Park, again showing how much brighter it is than the female:
In the UK, this butterfly has been the subject of mixed fortunes, and is now rather less common and less widely distributed than it used to be, decreasing by about a third since the 1970s. It is currently rarely found north of a line drawn between the Mersey and the Wash in Great Britain, although it can be found further to the north on the island of Ireland. Also in the damper west, it is less rigorously confined to woodland and may often be found even along hedge-banks. Internationally this butterfly is found across much of the Palaeartic, throughout much of temperate Europe and Asia.
The Silver-washed Fritillary is single-brooded with adults flying from mid-June until late August. The adults seem able to fly really fast through or across their home woods. As far as I can see, the whole of Dene Park, Clearhedges, Golden Stable Wood and Carroty Wood appear to form one ecological unit, so could be regarded as the home of a single inter-breeding colony. The adults feed in two distinct ways. They spend a lot of time in the canopy tops, feeding off sugary aphid honeydew. However they also often come down to nectar from flowers such as hogweed, where they are more easily seen and photographed. Adults are generally seen flying strongly along woodland rides and tracks, settling from time to time to rest or take nectar from flowers such as brambles.
After the couple of days required for maturation, the males spend a lot of time flying along rides and woodland edges and checking out glades looking for the females. A female may flicker her wings and perhaps release a scent from the end of her abdomen, which encourages the male to swoop duner and around her while she is flying directly ahead – a courtship flight I have been able to see in High Elms country park near Bromley. One of the loveliest things in life is to see a male looping continuously in the vertical plane around a female as it flies straight along, in their graceful nuptial dance.
One of the strange features of this butterfly is its habit of finding a woodland clearing with violets, the caterpillar food-plant, and then laying its eggs, often at a reasonable height, in fissures in the bark of nearby trees. This implies quite a journey for the newly hatched caterpillar n order to find its first proper meal!
The adults fly throughout July and August, and often lay their whitish eggs in regularly favoured locations, such as a woodland clearing. When egg-laying, the females fly into the semi-shady woodland and flutter slowly around the bases of trees, alighting to explore violet growth on the woodland floor. The eggs are laid singly in the crevices of tree bark or amongst moss, usually on the north or west side of the trunk. Most eggs are laid 1–2m above the ground but may be laid as high as 6m up a tree, or on other substrates such as dead Gorse. Both broad-leaved and coniferous trees are selected, but smooth-barked trees are avoided.
The hatched caterpillars simply eat their egg-shell, spin a pad of silk, and then settle down to hibernate for the winter. In the spring they finally travel down to ground level to search out violet leaves to feed from. They cut large semi-circular swathes of the leaves. The brownish caterpillars marked with orange may bask on dead leaves for long periods and up to a foot from the living clumps of violets they are feeding from. By June they are fully grown and climb back up onto trees in order to pupate, when they look like dangling dead leaves.
The larvae hatch after a few weeks but immediately enter hibernation. In the spring, they drop or crawl to the ground where they move over sparse vegetation seeking out violets on which to feed. During the day, they bask in patches of sunlight amongst the leaf litter, and when warm can move rapidly across the ground. Although they bask openly, they are well camouflaged and difficult to find, especially in hot sunshine. The few pupae that have been found in the wild have been 1–2m above the ground, suspended from leaves or twigs.
The main foodplant is Common Dog-violet (Viola riviniana) growing in shady or semi-shady positions on the woodland floor. To be honest, I haven’t seen all that many of these plants in those Hadlow woodlands where we can see the adults. They need light and this may be helped by regularly cutting rides and opening up clearings.
In southern England, a small proportion of females have wings that are bronze-green above, pinkish below, known as the form “valezina”. However, I don’t think it currently extends into Kent, and I have no photographs of it.
In some parts of the UK, although not the southeast where Hadlow is, the Silver-washed Fritillary is a priority species, so here is the fact sheet for those regions.
Predators and parasites
Birds take many, but still, the life of an individual adult may be nearly a month.