Mapping UK slugs


Help the RHS Plant Health team by counting the number of slugs living in your school grounds. This can be done as part of an after school club, STEM club, or as part of a science lesson. 

  • Estimated time: 45 minutes
  • Location: Outdoors
  • School term: All year round
  • Level of experience: No experience needed
  • Subject(s): Maths, Science, Geography

Learning objectives

  • Learn about slugs, what they eat and their preferred habitat
  • Work scientifically to collect data on the number of slugs in your school grounds
  • Understand how to use transect walks to measure distribution 


Explore your school grounds to find areas of different habitats including where slugs are often spotted, to help plan where your route will go. Examples include playground areas bordering on grass or near to edible crops or compost heaps.  


  • Torches (if dark)
  • Wet weather gear
  • Recording form
  • Pencils
  • Meter measure wheel or map
  • Your selected garden route

Extended equipment list:

(See step 7, hints and tips)

Step by step

Slugs damage plants and crops in gardens every day. Through this activity we are inviting schools across the UK to help us map slug populations and understand more about whether climate and geography affect their numbers. We have partnered with the Institute for Research in Schools (IRIS) to carry out this exciting activity and the Slug It experiment.  

To map the slugs in your school grounds you will need to count the number of slugs you find on a set route. The best time to find them is in the first two hours after sunrise or at dusk, towards the end of the school day.  During the daytime slugs shelter in the rims and on the underside of pots and containers, so you will need to investigate and be more observant.  

  1. Determine your transect walk by using a meter measure wheel or mapping software to plan an 800m route around your school grounds, preferably passing different habitats and plant types.
  2. Mark out your transect walk route in the schools grounds or draw a scale plan of the route to follow as a map.
  3. Decide when you will carry out your slug counts. We recommend once a month for at least six months but counts can be carried out more or less often if you wish, and even a one off count can be added to the UK map! When carrying out slug counts you must record the time of the counts on the recording form, each time you upload your data.
  4. Walk your route at a slow pace so that it takes 20 minutes to complete. Search 1 metre either side of you and count any slugs that you can see. 
  5. Record the number of slugs you count onto the recording form at To submit the form you will need to enter your school name, postcode, date of count, time of count, number of slugs found and the habitats. The rest of the form is optional to fill in. 
  6. Your data will be uploaded to an interactive map so you can see how your findings compare to those of other schools. The map will appear on the bottom of this page 24 hours after submission.
  7. Why not go a step further by collecting the slugs you find and trying to identify them by clicking on the images in this helpful key. You can also use the 'Identify a slug - body parts' spotter guide and 'Identify a slug - student sheet' to identify the slugs you find in your garden. 

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