Monday, 23 August 2010

BUTTERFLY: White-letter- and Purple Hairstreaks at Brockholes Wetlands, Lancashire

August 22 (and July 11), 2010:
The first decent weekend's weather for more than a month meant that many butterflies and dragonflies were on the wing on the Reserve. Six weeks ago, I was fortunate to obtain photos (above and below) of White-letter Hairstreaks (Satyrium w-album) there. Since then I had been hoping to get the chance to do the same with Purple Hairstreaks (Neozephyrus quercus). Boilton Wood at the Reserve's northern edge has both of these rather similar-looking butterflies and without doubt merits its SSSI status as a wild-life haven. White-letter Hairstreaks are closely associated with Elm trees (Ulmus spp.), especially Wych-elm, as this is their larval foodplant. Like many Hairstreaks they spend much time high in the tree canopy but will come down for nectar under favourable conditions. On this very warm sunny afternoon in July (the 11th), the weather was ideal, the bramble thickets below the trees were in full flower, and it was there that at least three of them were feeding on the brambles.

Being small, they were most easily located when in flight and needed to be watched carefully to find exactly where they had settled. Unfortunately, the subsequent poor weather appears to have curtailed their reappearance and it may be that this particular colony is only a small, somewhat isolated one. No doubt though, there will be several others elsewhere in these extensive woodlands.

Purple Hairstreaks (photos below) have a later and probably longer flight period. These are found amongst and close to oak trees (Quercus spp.) as this is their larval foodplant and, similar to the White-letter, they fly high in the leafy canopy and are also difficult to locate.

Today (August 22) they could be seen on two separate oak trees in warm but breezy conditions. It is interesting that they occurred in an almost identical situation to that of the White-letters although at a different place along the woodland's edge; they have in fact been seen in at least three separate places here recently.

When looking for both species this summer, even though conditions appeared ideal and the butterflies were known to be present, there were long periods of inactivity with none visible. Patience is needed to locate them.

[Typical habitat of both Hairstreaks, Brockholes]

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