Overseen by the UK Butterfly Monitoring Scheme https://ukbms.org/about
This involves volunteers walking weekly along a chosen route and counting all butterflies seen during a 26-week period between 1st April and 29th September each year
The map shows the transect that we started last year in Hartland —>>>
Butterflies act as important indicators of the health of the environment.
Monitoring their numbers enables us to assess the impacts of climate change and the effects of national and local policy initiatives.
Their rapid lifecycles and high sensitivity to environmental conditions make them a highly effective indicator species.
Establishing a Transect and How to Record
- Transects should take about 45-60 minutes to walk and be about 1mile in length.
- Identify a route (transect walk) that provides a fair representation of the habitats and other features
present at your site.
- This transect is ‘fixed’, in other words the same route should be followed each year
- Recording takes place once a week from April 1st to the end of September.
- Transect counts should ideally be made between 10:45 and 15:45 hours.
- Transect walks should only be carried out in warm (13 C or more) and at least bright weather. The
minimum criteria are 13-17C with at least 60% sunshine, or over 17C and not raining.
The figures below were collected by David & Caroline Warnes. If you would like to create your own transect please contact David at admin@hartlandnaturesociety.org.uk
Butterfly Transect Total Number of Butterflies Counted 2024 vs 2025
As you can see there were a lot more butterflies in 2025!
It is thought that although there were fewer opportunities for breeding and egg laying during the cool, wet and dull conditions of 2024, the more favourable weather in 2025 resulted in better survival rates even if the numbers of eggs/larvae were low.
One of our most common summer butterflies. They rest during winter in their caterpillar stage. The reason for showing this graph is to point out that in 2025 the adults emerged in great numbers many weeks before they did in 2024. The early, warm and dry weather is the most likely reason. Their numbers, along with many other butterflies, were much higher in 2025
This Striking butterfly migrates from North Africa and continental Europe to reach our shores each spring. The adults usually emerge in June/July from eggs laid by the immigrant females. Numbers greatly increase as the summer continues, particularly in 2025. I am sure we all remember seeing many, particularly on buddleia.
We saw no Spring Adults in 2024 compared to 2025. The weather conditions may have made it particularly difficult for adults to survive their trip.
Orange Tips develop into adults 1st after overwintering as pupae. Their foodplants, especially cuckooflower and Garlic Mustard are prevalent in the spring
Red admiral adults have a small peak when they reach this country and a much larger peak later in the summer when the initial eggs complete their life cycle
Meadow Brown caterpillars feed on a number of grasses and adult levels rise quickly mid to late spring.
Speckled Woods often have 3 life cycles throughout the spring and summer hence their level is more constant