In Depth: Scarce Blue-tailed Damselfly at Ughill Farm

When volunteer ecologist Wendy Birks recorded a scarce blue-tailed damselfly Ischnura pumilio at Ughill Farm, she discovered the species had never been logged in this area before. This raised question she wanted answers to! Here is her report:

Scarce Blue-tailed damselfly Ischenura pumilio at Ughill Farm

by Wendy Birks

This is a map of the distribution of Ischnura pumilio from the NBN Atlas in August 2026. There are no records from the Sheffield area or anywhere within at least 50 miles. So, the question is how did the species arrive at Ughill Farm? And why is it here? We might ask, should we try to look after it now it has arrived? 

To answer this look at the species’ecology, current distribution, habitat requirements and dispersal method.

The univoltine species needs relatively warm water in which its larvae can rapidly develop and adults eventually emerge in May and June. It is essentially a Mediterranean species. In the British Isles such conditions are provided where water bodies are relatively shallow and sparsely vegetated so that the water is warmed by the early season sunshine. This species’ “natural” habitat is shallow bog pools, seepages, flushes and valley mires where the temperature is sufficient for all life stages to develop. The key feature is sparse vegetation rather than the pH. This explains the occurrence over much of Ireland, Wales, the SW of England and around the New Forest, as this is where these peatland/wet heath habitats are to be found and the climate is at its mildest. Presumably  traditional management practices including seasonal grazing, ditch maintenance, rush cutting,even peat cutting etc. would have maintained the right conditions for the damselfly to persist. 

However, by the end of the 19th Century this species was thought to be extinct. By the early 20th C there were recognised colonies in just two counties in England and 3 counties in Ireland. There were also well-documented and reliable reports of the species being seen in places away from mire/wet heath vegetation but the consensus amongst the experts was to discount these as misidentifications. So the idea that the species was restricted to peatland/mire habitats persisted. However, in time, entomologists began to accept that the species was inhabiting locations outside its formerly accepted range and the understanding of the species’ requirements became better understood. It is now realised that certain human activities were creating the ideal conditions for this species. Quarrying, digging pools and pits, even warfare, provided the early successional and specific microhabitats that this species favours. Examples are: the coal mining areas of Wales and the Forest of Dean, tin and china clay mining in Cornwall, bomb craters in Dorset. These industrial activities provided unvegetated seepages and runs, shallow pools, puddles and impressions left by vehicle tracks; all the type of paces used by Scarce Blue-tailed Damselfly. This unintended habitat creation allowed the species range to move eastward. Presumably, in more recent times, climate change is also playing a role by resulting in a trend towards more “Mediterranian-like” conditions over much of the British Isles. This means that, unlike former times in the 10th and 20th centuries, temperature is no longer a limiting factor to the distribution of the species (in England at least). 

So, how did, what are actually rather small creatures (abdomen 21 – 25mm and hindwing 14 – 18mm (Brooks and Cham 2014)) get to Ughill Farm?

Dispersal takes place on warm and sunny days when the adults have been seen to fly vertically, to where it is thought rising thermals may take them into the path of prevailing winds (which, in the British Isles, are generally from the west and southwest (Wikipedia). This would explain how they might travel 50 or more miles from one of the recorded sites on the NBN Atlas, to colonise a new location at Ughill. It may not be as simple as this though. It is possible that the species has come from nearer by, but its location has not been discovered by a species recorder and reported to a wildlife database. However, this suggestion needs to be qualified; this species’ requirements are rather specific and are not very common, and once they do occur tend not to persist for very long. A new scape, puddle, tyre track may soon become vegetated and shaded, especially as nitrogenous, phosphorus-rich air and/or water pollution promotes lush plant growth. The species could be present for a few years at a site where it is never seen by anyone with the knowledge to identify it, and therefore go unreported. It is even possible that Scarce Blue-tailed Damselfly has been on the farm for a while, and gone unnoticed; the farm possesses some suitable and perhaps marginally suitable habitat in fields 7 and 8. 

So, why has this species arrived at Ughill farm? What has attracted it? I saw the adults flying among the grass shoots emerging from one of the recently created ponds that are fed by the seepage that crosses fields 7 and 8. 

The photo on the right above shows the habitat in one of the three newly created ponds on Ughill Farm; it can be seen that the vegetation is sparse and the water unshaded. At the time the habitat  matched the requirements for Ischnura pumilio. As of August 2026, this pond and its two neighbours are completely surrounded by tall herb vegetation, however, they must still be open enough for the damsels to choose this site. The photo below shows how the vegetation has developed in less than a year. 

The Glyceria will provide suitable ovipositing sites for the female damselflies, should any be present. They lay their eggs into the tissue of the grass stem just below the water surface. Here they remain moist, even if the water level drops and the pond dries out. The eggs hatch and the larvae go through several instars, the speed of development increasing as the winter declines into spring. The adults emerge May – June. Over the next few years these ponds will become unsuitable for this species. The trees from the tree planting will shade them, the Typha will grow to fill the pond. 

On Sunday 09/08/26 when I spotted the species, it was two males I saw. I don’t know if females have been present. I will certainly be keeping a look out for them, though note the flight period is coming to an end. In spring I, with the help of Fiona Jones will do some pond dipping to look for larvae. Plus, David Pritchard from the British Dragonfly Society wants to visit the farm to see the species. Hopefully that can be arranged to take place soon. 

It’s up to others to decide if Ughill Farm habitats should be managed to make space for this species. A list of techniques for managing the habitat is provided below. 

The microhabitat requirements must be understood if this species is to persist at a site.

1. Maintain the water quality and quantity  to meet the species’ needs. At present, Daylight Dike and the seepage across fields 7 and 8 appear to be doing this. We also have vehicle tracks and the shallow water crossing the main track up to fields 20 and Furnace Hill. 
2. Restrict the growth of submerged and emergent vegetation that would otherwise create shade and hence lower the water temperature. This will probably not be achieved in the three ponds created as part of the tree planting project; here natural succession will cause the ponds to become colonised with willows etc. and the trees will inevitably grow up and completely shade the ponds. However, the new Newt Ponds and their associated scrapes may serve the purpose. Up to 2026, fields 7 and 8 have been managed by cutting and aftermath grazing. The rushes in particular being cut on rotation to create habitat for breeding waders. If and when the rushes are cut around the Newt Ponds, this will, help maintain the open vegetation and allow the pond water to warm (how this fits with newt biology I am not sure). Using the cattle to create trampled muddy edges where creeping grasses, including Glyceria fluitans which are already present, can grow will also help to control the growth of the vegetation. Will these Newt Ponds ever develop a fringe of scrub and dense emergent and submerged vegetation? Probably not as the fields are being used for agriculture. It is possible that the shallower ones will continue to provide habitat for Ischnura pumilio. 

As  fields 7 and 8 are left undisturbed between February and May to allow the waders to breed without disturbance, we will not be able to net the ponds to search for damselfly larvae. On 25/07/26 Fiona, Sandra and myself took samples of aquatic invertebrates from one of the new Newt Ponds in field 7. The samples are not all identified yet, but we do know we did not find any Odonata larvae. These ponds were not created until November 2025, so there would not have been time for many species to colonise the ponds. However, before the ponds were there, there was a permanent seepage which may have been providing suitable habitat for I. pumilio. We intend to sample the area again next year, or possibly before then. Obviously we will be looking for the larvae of Scarce Blue-tailed Damselfly. 

Note: The information on the ecology of this species comes from an article written by Steve Cham and published in British Wildlife Magazine in April 1996. I believe the full article is available from British Wildlife Publishing for a fee. I have a subscription, which is how I came across it.