Current status
This large and spectacular fly is found in unimproved grassland and heath in southern England and Wales. However, these habitats have shown significant decline in range and quality in recent years, with fragmentation enhancing the difficulties facing this insect. Since 1970 the hornet robberfly has been recorded from only about 40 ten km squares: in Hampshire, for example, it has been lost from six of its seven chalk grassland sites over the last few years.
The fly`s larvae are believed to prey on the larvae of large dung beetles and the adult flies feed on a variety of insects, including grasshoppers, dung beetles and flies. As such, it requires suitable grassland sward to support its prey community.
Current factors causing loss or decline
Loss of unimproved grassland and heath leading to habitat fragmentation.
Use of persistent parasite treatments for stock (e.g. ivermectins) which kill dung beetle hosts.
Changes in stock management.
Current action
A population on a National Trust property in Wiltshire has been monitored for several years by the warden.
Two SSSIs in Wales are under management agreements to ensure that agricultural usage is consistent with the needs of the robberfly.
Action plan objectives and targets
Ensure the continued survival of the species in England and Wales in at least 40 regular sites.
Proposed actions with lead agencies
Policy and legislation
Produce a policy statement on the use of ivermectins in SSSIs and nature reserves. (ACTION: CCW, NE)
Ensure that the effects of new veterinary chemicals on non-target species and their environment are taken into account when considering approval for release of these product for general use. (ACTION: MAFF, WOAD)
Site safeguard and management
Consider trial land management schemes in about five areas where the robberfly occurs, to test the effects of alternative methods of grassland and stock management on this species. (ACTION: CCW, MAFF, WOAD)
Promote favourable management in all SSSIs and nature reserves where the species occurs or formerly occurred. (ACTION: CCW, NE)
Species management and protection
No specific action proposed.
Consider notifying strong populations as SSSIs.
Advisory
Produce a leaflet on appropriate management for circulation to land owners and managers of sites where the robberfly occurs, or was once present. (ACTION: CCW, NE)
Future Research and Monitoring
Survey sites or districts where the species has been reported since 1960, to determine the current distribution. (ACTION: CCW, NE)
Promote research into the fly’s ecology, especially its habitat requirements, population dynamics, dispersal abilities, larval hosts and adult prey and the importance of metapopulation structure to their survival. (ACTION: CCW, NE)
Promote investigate into the effects of ivermectins on the robberfly, and the use of alternative methods of stock parasite treatment that are less harmful. (ACTION: MAFF, WOAD)
Encourage monitoring of known sites for this species, seeking to include, where possible, information provided by local naturalists and site managers on the history of site management and the effects of ivermectin treatments on local robberfly populations. (ACTION: CCW, NE)
Pass information gathered during survey and monitoring of this species to JNCC or BRC so that it can be incorporated in national databases. (ACTION: CCW, NE)
Provide information annually to the World Conservation Monitoring Centre on the UK status of the species to contribute to maintenance of an up-to-date global red lists. (ACTION: JNCC)
Communications and Publicity
Use this large and attractive fly to highlight the conservation issues facing insects associated with dung. (ACTION: CCW, NE)
Links with other action plans
None given.
Publication details
Originally published in: Biodiversity: The UK Steering Group Report - Volume II: Action Plans (December 1995, Tranche 1, Vol 2, p124)
Related links
ARKive Visit the ARKive website to view images and further information relating to this species