The Small Pearl-Bordered Fritillary was not recorded on the Hampshire-Wiltshire border in 2022 , suggesting that the species is most probably extinct there.

Compared with the photograph (below-right) this was the scene in the car-park in June 2021, compared with the scene in the car-park in 1984...my have things changed!

Bentley Wood

Bentley Wood NNR
A Wildlife Haven

The Pearl-Bordered Fritillary can be quite common along the rides and in the meadows created in the woodland over the years. Here a male is resting on Bugle in May.

The main attraction to visit this site over the years has been the Purple Emperor butterfly. It can be seen in the main car-park where it is attracted by the cars and people watching the skies for any movement! Its also seen along the rides but stealth and a lot of patience is needed and always be prepared for disappointment.

The Small Pearl-Bordered Fritillary is now one of the rarest butterflies in Hampshire and is very rare in Bentley Wood. In 2022 it was not recorded on site suggesting it may well be extinct now.

The Argent and Sable Moth is a very rare moth and Bentley Wood is one of the few places where it can be found, laying its eggs on Silver Birch saplings.

Head of a Pearl-Bordered Fritillary

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View along The Switchback from the car park, with the log book in the noticeboard where you can see what has been seen and also log species seen, the banana skins are put on top of the notice board to attract the Purple Emperor although I've never known it to alight there

Highlights

Large mixed woodland on Hants/Wilts border.
Nationally recognised for its importance as a butterfly site.
Every woodland species resident in central southern England is found in the wood, including Pearl-bordered and Small Pearl-bordered Fritillary.
Duke of Burgundy present in small numbers and a few Marsh Fritillary recorded in most years.
Known nationwide as a good site for Purple Emperor.

Description

Bentley Wood is large mixed woodland on the Hants/Wilts border - and yes, OK, so most of it is in Wiltshire! Its importance as a butterfly site is nationally recognised and reinforced through its designation as a Site of Special Scientific Interest (SSSI). More than 35 butterfly species are recorded there regularly, including every woodland species resident in central southern England including, of course, the enigmatic Purple Emperor for which it is probably best known. There are also populations of Silver-washed Fritillary, White Admiral, Purple Hairstreak, Pearl-bordered Fritillary and Small Pearl-bordered Fritillary. In the case of the latter, Bentley Wood probably has the only remaining colony in Hampshire, although sadly now in low numbers. In addition, White-letter Hairstreak, Duke of Burgundy and Marsh Fritillary also retain a presence within the wood.

For visitors approaching from Hampshire, the Tytherley Road entrance is probably most convenient. The car park is reached after about ½ km drive along the track. To see the small fritillaries (Pearl-bordered, Small Pearl-bordered and sometimes Marsh Fritillary), go to the Eastern Clearing (map) by heading on foot 100 yards back down the track, then take the footpath bearing to the left into the clearing The Pearl-bordered are first on the wing - from early May, with Small Pearl-bordered appearing typically in the third or fourth week.

The populations of both Pearl-bordered and Small Pearl-bordered Fritillaries have been declining in recent years, the status of Small Pearls, in particular, giving serious cause for concern. Pearl-bordered Fritillaries are found both in the clearing and also along some of the open rides in the wood. Small Pearl-bordered Fritillaries favour the damper areas in the clearing, including the more recently cleared sections just to the north. Several Small Pearls seen during a visit would be considered a good outcome. Duke of Burgundy is usually recorded during May in very low numbers - look for them in the drier, more tussocky areas of the clearing. In most years, a few Marsh Fritillaries are also reported from the clearing, perhaps as a result of sporadic breeding, or dispersal from nearby sites in Wiltshire.

If your visit is in July and aimed at the Purple Emperor, they are generally most active during the mornings, so be there early (eg 9 am). The end of June through until mid-July is usually the best period. Bright or broken cloud conditions with little wind seem to be optimum, but the species is unpredictable. The car park is a good place to wait since the males will occasionally swoop down from a nearby oak and do a circuit or two - sometimes landing briefly on a shiny metallic car or a tyre which has the remnants of dung on it! Visitors occasionally put well-ripened fruit on top of the visitor board to attract Purple Emperors - and with some success. Other productive Emperor locations (with some groundings) include the track - called the switchback - which heads west from the car park as far as the first major cross-tracks, and also the track heading south from this junction to Donkey Copse, where there is also an assembly point for aerial views.

During Emperor time, Silver-washed Fritillaries can be common (late June and through July) and there can be an unusually high proportion of the normally rare female aberrant form, called valezina, where the golden-brown background colour is replaced by a greenish bronze. A few White Admirals can usually be seen during this period, intricately gliding along the boughs or pausing to feed on brambles.

There are several small colonies of White-letter Hairstreak around the wood, the best known being close to the Ralph Whitlock memorial. Turn right at the first cross-tracks on the switchback, continue through a slight depression and across another set of cross-tracks until the main track is about to turn right. There are several Elms facing you on this bend (map) which are home to a colony of White-letter Hairstreak. The memorial is a few yards down the minor track to the left where there are more elms (some diseased) and elm suckers, which are also worth a look for White-letter activity.

If your visit is not particularly aimed at a particular species, but simply because Bentley Wood is a unique woodland butterfly site, then exploring some of the different areas of the wood, each with its own characteristics, is recommended and can be very rewarding.

1980's and High Brown Fritillary was still present

The High Brown Fritillary was never common in Bentley Wood, however when I first started to visit the site in 1984, I found several individual specimens, and one season later on in the late 80's I found a pair mating in a high bush on the ride that leads up to the main ride . They used to be found in the Eastern Clearing, with the Dark Green Fritillary. However the High Brown Fritillary is now extinct and the Dark Green is very scarce.

One of the most common moths found in the meadows is the Speckled Yellow Moth.

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Eastern Clearing is now drying out and many of the species seen when this photo was taken in 1986 have since disappeared or are disappearing.

Wych Elm trees in Bentley Wood are quite common so look for the White-Letter Hairstreak flying around the tree tops.

Marsh Fritillaries have been common in Bentley Wood especially on the Hampshire Border in the 1980's there was a very large colony there, which has since died out. They can still be found on the Wiltshire side of the border in certain meadows in the wood.

The woodland Duke which feeds on Primroses is a rare butterfly in Bentley Wood. The Primroses grow in the gullies in the meadows and the Duke is found in the meadows on both sides of the border in very small numbers.

The Purple Emperor attracts visitors from all over the country and sometimes abroad. In the 1990's it was probably the best site to go to, however over the last decade its lost its crown to a couple of other sites, including one in Hampshire.