Hoverfly lagoon

RHS School Resource
A little water can go a long way in helping hoverflies as the larvae of several species live in leaf-filled pools. Make hoverfly lagoons to attract vital pollinators to your school grounds

By The RHS School Team

Hoverfly lagoons in school garden

Quick facts

Learning objectives:

To understand what hoverflies are and why they are important for our ecosystem

1

To identify what hoverflies and their larvae need to survive

2

To create a micro-habitat to support wildlife

3

Science: Find out about wildlife habitats and how living things depend on each other

4

Geography: Learn about the effects we can have on the natural world

5

Key vocabulary

Wildlife | Habitat | Hoverfly | Larvae |

Equipment

  • A waterproof container, ideally upcycled and that hasn’t been used for any chemicals or harmful products in the past (a two or four pint empty, clean milk carton, cut in half, is perfect)
  • A tray that fits generously underneath your container
  • Water

Introduction

  • Introduce pupils to the Wild About Gardens 2025 hoverfly campaign by downloading the booklet to look at habitats, activities and identification guides together
  • Show pupils the hoverfly lagoon demonstration video (the drainage holes aren’t essential and should only be done by an adult)
  • Ask pupils whether they’ve seen hoverflies before, and what they’ve noticed about them
  • Go on a short hoverfly hunt around the school grounds – encourage pupils to notice where they are located (around tree hollows, sunbathing on leaves, close to -friendly flowers)
  • Explain that many hoverfly species (including batman hoverflies and the marmalade hoverflies) require pools of water to breed, as their larvae live in water
  • Demonstrate how to make a hoverfly lagoon using the instructions below

Main activity

Pupils move around the garden or outdoor space and collect dried leaves, sticks and other organic matter.

Pupils make a hoverfly lagoon using the following instructions:

  1. Place your container in the tray.
  2. Fill your container with leaves and organic matter, up to about 2cm from the rim, compacting the contents as you go.
  3. Add a few sticks to your container, pressing everything down as you go so they touch the bottom of the container but still poke out above the top – these will act as hoverfly lifeguard towers!
  4. Pop the lagoon in a quiet spot in partial or complete shade – ideally underneath a tree or bush.
  5. Add water to the container, filling it up to 2cm from the rim.
  6. Add a layer of leaves to the top of the water and in any free space on the tray.

Hints and tips

  • Watch this short tutorial by RHS Scientist Josie Stuart
  • Keep your hoverfly lagoon topped up with water – particularly during the warmer months
  • Head to our Wild About Gardens website to download your free hoverfly booklet and make a pledge to be a hoverfly hero
  • Use our spotter guides to help you identify hoverfly larvae and adults

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