The pine hoverfly is one of the most threatened species of insect in the UK, it is critically endangered and, prior to the Conservation Breeding and Release programme was restricted to only one site in the Cairngorms.
It is a flagship species for high quality, diverse Caledonian pine forest and plays key ecosystem roles both as a pollinator and a waste recycler as part of the fauna of Scotland’s boreal pinewoods.
Surveys undertaken by the Rare Invertebrates in the Cairngorms (RIC) project identified the precarious state of the pine hoverfly population. In response, the pine hoverfly Steering Group took the decision to collect pine hoverflies from this population. In 2018 the Royal Zoological Society of Scotland established a breeding and release programme at the Highland Wildlife Park and has been successfully breeding pine hoverfly ever since.
Since the first breeding cycle in 2019, over 23,000 larvae have been released across four years. Ongoing monitoring has revealed some impressive milestones, with the first adult spotted in the wild in nearly a decade and proof of breeding in the wild also discovered.
Male and female pine hoverflies differ slightly in appearance. Males have larger amounts of orange on the abdomen and no gap between their eyes whilst females have only orange at the tip of their abdomen and a gap between their eyes.
These small flies have had amazing success, however, changes in forest management and continued breeding and release are needed to save one of Scotland’s most threatened insects.
Images: © Royal Zoological Society of Scotland
Action Needed
- Support long-term funding for invertebrate species such as the nature restoration fund.
- Advocate for the inclusion of pine hoverfly in long-term forest plans and forestry strategy.
- Support engagement with local landowners to secure further release sites.
Threats
Habitat loss – A lack of complex forests in the landscape with both veteran Scots pine and flowering plants present. Pine hoverfly larvae use wet rot holes in Scots pine; this is typically formed from windblown trees that snap leaving the holes to fill with water. The holes must hold water throughout the year to host the larvae successfully. Adult pine hoverflies feed on the nectar from flowering plants and work at RZSS has shown a preference for rowan flowers in captivity. Due to land use changes, commercial forestry management and felling, removal of deadwood, and loss of mature Scots pine, there has been a decrease in the number of natural rot holes for larval development and suitable habitat for pine hoverflies.
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