School of Life Sciences, JMS Building, University of Sussex, Falmer, Brighton

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Hoverfly Lagoons

The decline of pollinators in the UK and worldwide is of real concern, potentially leading to a pollination crisis and affecting flowering plants and crop yields. Much of the attention and research has been around bees, but other pollinators are similarly important and help enhance the pollination services that our crops and plants receive.  This project focuses on hoverflies - an often overlooked, yet vital part of our wild environment.

Hoverflies are true flies ('Diptera'), more closely related to  bluebottles than to bees, but are often mistaken for the latter because of their yellow-and-black patterns.  This is no accident, since hoverflies mimic bees and wasps for defence, although they cannot sting and do not live in nests.  There are more than 280 hoverfly species in the UK, and Hoverfly Lagoons focuses on those that have an aquatic lifestage, with larvae that live in pools of water or 'rot holes' in trees (particularly the genera Eristalis, Myathropaand and Helophilus).

Our gardens often lack these aquatic habitats, providing little egg-laying space for the flies, thus Hoverfly Lagoons encourages you to create small homemade hoverfly havens from discarded milk bottles and fallen leaves. We want to work out what are the best ways to make these lagoons - so we need your help, and gardens!


Lagoons are a quick way to add wildlife habitat to your garden.  Taking part requires no extra knowledge or experience, just a few minutes each month to count larvae and collect pupae, once the lagoon is set up.  Check out the project video below to learn more about lagoons:

Name:            Hoverfly lagoons

Year(s):           2016 -

Focus?           Hoverflies

Status?          Ongoing

Results?        Ongoing analysis

Project lead contact:

Dr Ellen Rotheray

Project summary

This project is good for kids!

"Lagoons are messy fun, and can be packed full of long-tailed larvae to discover. Children can get involved collecting pupae and observing them until, like butterflies from the chrysalis, the stunning adults emerge" - Dr Ellie Rotheray

Taking part in Hoverfly Lagoons

The project runs from May - October, which is when the hoverflies are flying and breeding, although setting up your lagoons earlier gives them time to get nicely rotten.  You will need:

  • A 2 or 4 pint plastic milk bottle

  • Scissors and a pen, for poking holes

  • A tray with drainage holes

  • A basin

  • A jar or insect tube

  • Sticks, leaf litter and / or grass cuttings.

Once your lagoon is set up we will ask you to check the material once a month for the long-tailed larvae, and record how many individuals you find. Towards the end of the project the number of pupae found in the trays can be recorded. The pupae can then be transferred to jars until emergence to allow for identification to species level.

Full instructons can be downloaded here, along with other project documents:

Lagoon                                        Hoverfly
methods                                    factsheet

HL methods.png
HL facts.png

Ellie demonstrates how to create and survey your lagoons.  Featuring some very chunky long-tailed larvae!

Let us know if you are making a Hoverfly Lagoon! 🏖️