The pine hoverfly is arguably the most endangered hoverfly in the UK.
Pine hoverflies in the UK
The RSPB is involved in the conservation of a variety of plants and invertebrates on our nature reserves and elsewhere.
- Phase of recovery: trial management
- Red data book: endangered
The problem for pine hoverflies
The pine hoverfly is arguably the most endangered hoverfly in the UK. It has always had a restricted range, but was regularly recorded in Strathspey and Deeside, in Scotland, up to the 1940s. Since then, it has dramatically declined and in the late 1990s surveys by the Malloch Society (a specialist academic organisation that studies flies), funded by Scottish Natural Heritage, found only two remaining populations of this species, both in Strathspey.
The pine hoverfly is also declining in Europe, where it is restricted to mountainous areas. The pine hoverfly needs rotten tree stumps that are more than 40cm across to breed. The lack of these large stumps in pinewoods – especially stumps with the necessary rot conditions – has been the cause of the decline.
Searching for signs of the hoverfly
Pine hoverflies were last seen at what is now the RSPB’s Abernethy reserve in the Highlands of Scotland in the early 1980s. By the late 1990s there were none at Abernethy and only two breeding populations remained in pine woodlands in Strathspey.
Since then, the RSPB has worked with partners to supplement the breeding habitat and commenced a trial translocation programme.
The hoverflies need wet rot conditions in which to lay their eggs, so experiments to replicate these conditions were carried out by cutting holes in stumps and filling them with different materials. Within six months, holes filled with wood chips had been used for breeding and the presence of empty puparia showed that the breeding cycle had been completed.
A successful increase in numbers
Providing artificial sites with suitable conditions for the pine hoverfly to breed has been successful at the first trial site and we believe that this work has added 65 hoverflies to the adult population. The hoverfly hasn’t yet occupied artificial breeding sites at other locations, including the RSPB’s Abernethy reserve, but these have only been in place for one year, so we are still hopeful.
At a second site, a community woodland, we are monitoring natural and artificial breeding sites and the needs of the species are taken into account in the management plan which is being developed for the site.