The foraging ecology of hoverflies and the potential for manipulating their distribution on farmland.

  • Published source details Cowgill S.E. (1991) The foraging ecology of hoverflies and the potential for manipulating their distribution on farmland.


This study is summarised as evidence for the following.

Action Category

Leave headlands in fields unsprayed (conservation headlands)

Action Link
Farmland Conservation
  1. Leave headlands in fields unsprayed (conservation headlands)

    A replicated, controlled study of two headlands over two years 1989-1990 in England (Cowgill 1991) found that in 1990, there were significantly higher proportions of some species of hoverfly (Syrphidae) adults (marmalade hoverfly Episyrphus balteatus, Metasyrphus spp.) in conservation headlands (20-24%) compared to fully sprayed headlands (9-12%). There were also higher proportions of E. balteatus adults feeding and lower proportions inactive in conservation (feeding: 15-90%, inactive: 0-85%) compared to fully sprayed headlands (feeding: 0-35%, inactive: 0-100%). Behaviour of Metasyrphus corollae did not differ with treatment. There were no significant differences in 1989. Weed density and floral area tended to be higher in conservation compared to sprayed plots. Headlands were divided into three or five replicate plots of 75-100 m x 12 m wide, each containing the two pesticide treatments. A set route was walked to record hoverflies encountered during a fixed time period. Weekly counts of weeds and hoverfly eggs on wheat were made in 15-21 quadrats/plot from May-July. Aphids (Aphidoidea) were also recorded but results are not included here.


Output references

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, terrestrial mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 18

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust