Slugs count

The RHS and Newcastle University are carrying out a year long study with members of the public to understand the slugs in our gardens better

The last major study of slug diversity and activity in gardens was carried out in the 1940s by entomologists Barnes and Weil.

Things have changed since then, both in the way we manage our gardens but also in the slugs present in the UK. Many more species of slug are known to be present and established in Britain since the 1940s, and some species such as the cellar slugs are known to have a changing distribution.

Learning more about which species are present and the most abundant in gardens is important for understanding the impact they may be having and will help inform the advice the RHS gives the public.

We have recruited and trained 60 volunteers from all around Britain to take part in a one-year study investigating slug activity in their gardens.

Our participants are:

  • Surveying their gardens at night for 30 minutes every four weeks for a full year
  • Collecting the slugs they find, attempting to identify them, and sending them to our scientists

Sampling started in October 2020 and is due to end October 2021.

Who is running this project?

This project is part of a PhD project by a post-graduate scientist, Imogen Cavadino, with Newcastle University, the Royal Horticultural Society, and the UK Centre for Ecology and Hydrology, who are collaborating to combine their expertise on slug and snail biology, and biological recording.

The overall aim of this project is to identify which species of slug and snail are present in UK gardens, which are causing damage to plants, which may be beneficial, and their abundance. The results of the project will be communicated back to survey participants and published on the web and in horticultural media for the public. It will also be used to improve the advice the RHS gives to the public.

Map showing where sampling of slugs is taking placeWhat stage is the project at?

Sampling is taking place across mainland Britain (see map). Applications to take part in the project opened on  20 January 2020 and closed  on 2 March 2020. We had an incredible 2,970 applications! It was very tough narrowing this down to 60 participants, but the final participants have been chosen and trained in slug identification techniques.

Unfortunately the project start was delayed due to the COVID-19 pandemic, but is now back up and running. Participants started surveying their gardens every four weeks from October 2020, with sampling due to end in October 2021.

If you have any specific questions about the “slugs count” survey please email us via: [email protected].

Slug hunting after darkWhat are the participants doing?

Our participants have committed to going out into their gardens once every four weeks after dark to walk a set route for 30 minutes, collecting any active slugs as you go. They are then trying to identify the slugs they find to genus or species level if possible, before sending them live to the project scientist. We have provided them with full training on slug identification, an identification guide, and continue to provide one to one support by email and/or telephone throughout the -project. 

Can I really post the RHS slugs from my garden?

Only if it has been confirmed that you are participating in the project! Please do not send in unsolicited slugs. If you have been accepted as a participant, only send in material that you have collected following the survey method explained above. Participants have been sent specific instructions on how to package and send live invertebrates to ensure they arrive safe and well.

Can I still take part?

All our places have now been allocated. However, you can still learn about how to identify slugs using the videos below:




What happens to the slugs posted to the scientist?

The slugs sent in are identified to species and checked against the original identifications participants have made. Live individuals of some species are used for a lab-based feeding choice experiments exploring their food preferences.

Some species require examination of the genitalia to confirm to species level, so where necessary these will be killed humanely and dissected. Tissue samples may also be kept for DNA testing to provide more information on species diversity. Where appropriate, voucher specimens of new or cryptic species may be sent to other institutions to support their research.

All material in good condition when received will be kept for reference in 70% ethanol, with suitable material added to the RHS permanent reference collections housed in our entomology department. These collections are used for research, reference, teaching and educational purposes and are an important scientific resource.

What happens to the personal data I’ve sent in?

The RHS is carrying out this survey as part of PhD research project to better understand the species of slugs active in gardens and the features that may influence this. We are collecting your data in order to allow our scientists to:

  • Contact you to discuss your participation in this project
  • Identify convenient locations for training sessions related to the project and invite you to attend
  • Send you materials required for the survey should you agree to participate
  • Encourage you to submit your data from the surveys you carry out in your garden and provide support for this
  • Contact you with news and updates about the project, including inviting you to event(s) exploring the project results, ask you for feedback, and/or inviting you to sign up to future related research projects at the RHS.

To do this we require your name, home address, email address and telephone number. We feel we have legitimate interest to do so. We will store this personal data for up to five years if you are selected to participate in the project, or six months if you are not selected.

Your personal data will be stored on internal RHS servers with access limited to the project organisers within the RHS’s Plant Health team. Your contact details will not be shared internally with other teams without your permission or with any other organisation except as a legal requirement and will not be transferred outside of the EU.

When you submit your survey records, your name will be included alongside the survey information (including location and time of record) to form the ‘biological record’. We may share the records you submit with partners, including the Conchological Society of Britain and Ireland (you can view their data policy here), and other nature conservation societies in the interests of wider scientific understanding and nature preservation.

These records will include your name as the recorder, but no further contact details. We will ensure that these partners keep your information secure through Data Processing Agreements. Anonymised versions of records with your name removed will be released as open data on the NBN Atlas (a collaborative project that aggregates biodiversity data from around the UK) or to other partner organisations who do not accept our Data Processing Agreement.

If you choose to give your consent, your name would also appear on labels associated with any slugs collected or identified by you and deposited permanently in our reference collection.

The RHS takes its Data Protection responsibility seriously. Please read our full Privacy Policy for more information on how we use your personal data and your rights under Data Protection.

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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.