Managing your Sallows for iris

We don’t particularly want to become a conservation body, as there already is an excellent organisation dedicated to the conservation of butterflies, and we don’t want to tread on their toes.  Also, some of us are actually a little jaundiced by the bureaucracy and failings of UK nature conservation movement… . 

But, Britain's premier butterfly is not vulnerable or endangered and isn’t even a BAP species.  BC classify it as a Species of Conservation Concern, which means they cannot prioritise it at present.  But we can, and we do. 

One thing we can lead on, with BC acting as a critical friend, is the development of advice on how to manage sallows for this butterfly (and we should include other biodi-but we refuse to allow that horrid word on this website). 

Please regard this as a working document.  The following advice should be regarded as provisional.

Please contribute your experiences and comment on what we are saying (and not saying). 

These thoughts are aimed at helping nature reserve managers, FC foresters and rangers, county council rangers, National Trust wardens & rangers, and so on. 

Frequently asked questions -

1     How do I get rid of sallows without upsetting Purple People?
Sometimes sallows have to go, full stop.  Lyn Fomison, warden of BC Hampshire branch’s Bentley Station Meadow reserve suggests ring barking inappropriate sallows in late May.  In theory then, any Purple Emperor larvae will feed up and pupate – adults will emerge – but the foliage will have wilted, and wont be laid on again.  The trees can then be felled.  Sounds great, please try it – but we’d rather you didn’t have to!

 

2     What sort of sallows does the Emperor like? 
At present, it seems that the Emperor strongly prefers Goat Willow Salix caprea, especially bushes that are shaded by taller trees (to the S and W).  Shaded Goat Willow with mid-green, soft, matt (upper surface) leaves are strongly preferred.  Female trees may well be preferred.  But, Goat Willow is rare in many Emperor woods, being replaced by a variable hybrid S. x reichardtii, which sometimes looks like Goat Willow (though with less round, more elongate leaves). 

3     What sort of sallows does the Emperor not like?
Trees exposed to full sun (unless they are large with dense mid-green foliage), trees with sparse yellow-green leaves, and narrow-leaved sallows (various species and hybrids) with small leaves are usually avoided.  You should not get hung drawn and quartered for felling sallows with these characteristics. 

 

4     How do I get sallows to germinate / increase?
Sallows germinate in bare, usually disturbed ground, especially in clayey soils.    

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5. Squirrels are damaging the sallows, should I cull them?

Grey squirrels bark-strip sallows quite badly, leading to weak crowns and sometimes tree death.  Within reason, bark-stripping may not be a problem if the sallows are shaded by tall trees, but along south-facing rides it may well render the bushes unsuitable.  Rabbits also bark-strip lower sections of sallow trunks in snow, heavy frost, drought or when their populations are high.