Butterfly Transect 2026
Clouded Yellow
Summer 2026 saw our first butterfly transect walk in Boston Spa, set up under the auspices and supervision of Butterfly Conservation.
This national charity set up a national network of transects in 1976 with the purpose of recording population trends of different butterfly species.
There are over 3,000 transects throughout the British Isles,and each one consists of a set route which is walked by volunteers each week between April and September.
All sightings are recorded and compiled on firstly a regional database (in our case for Yorkshire), then on a national one.
The same walks are repeated each year, so that regional and national trends over time for every species can be observed.
Of all living species, butterflies most accurately reflect the ecological health of our environment both in terms of habitat and climate.
We’re delighted to be able to contribute to the recording and collating of this important information. We hope also that the project will heighten interest among local residents in these fascinating and beautiful creatures.
We are grateful to our team of 18 volunteers who take turns to walk the route and record their sightings.
Our Boston Spa walk is in two parts:
1) a walk around Stables Lane Park with its mixed habitat of wild flowers, hedgerows, grassland and allotments; and
2) a walk through St Mary’s churchyard, across to the Church Fields wildflower meadow and back across the grassy area to the shrub and tree walkway next to the Church Fields car park.
The whole walk takes about 45 minutes.
The number of butterflies seen correlates very closely with the temperature. On the first 4 walks up to 1st May, there were in total 5 peacock, 2 small tortoiseshell, 2 holly blue, 2 orange tip, 3 green veined white and 4 small white. Modest numbers because the weather was cool.
During the first 2 weeks of May there were none as the weather was cold and damp which was of course disappointing for the volunteers looking in vain for butterflies.
The second half of May saw an insurgence of Painted Lady butterflies. These fascinating creatures migrate from sub-Saharan Africa, but they do this generationally so that each new generation continues the journey north through the spring. In some years there are none, in other years there are thousands, depending on how conducive the weather is to such a huge migration.
The first half of June was cold and damp again, so apart from 1 painted lady and 1 speckled wood, there were no butterflies to record. As the weather warmed in the second half of June, there were lots of meadow brown and lots of small and large whites, and good numbers of many more species.
Gatekeeper
By mid July when the weather was very warm, we had our peak numbers. Gatekeepers became very numerous, in fact there were 33 on one walk!
In August, as the hot weather took its toll on the hitherto glorious wildflower meadow (by mid August it was brown and dried up), species became far less varied so that by the end of the month there were only whites.
There were fewer butterflies to be seen in September, partly because of the cooler weather, but in part because some species’ breeding patterns mean that they are no longer around.
Peak numbers for meadow brown, for instance, are in June and July, and for Gatekeeper in July and August.
The only species seen by our volunteers in September were small and large white, and red admirals. The breeding season of these whites, as vegetable gardeners will testify, is prolonged, and their numbers are reinforced by migrations from continental Europe.
Red Admiral
Red admirals are a migratory species from continental Europe as very few adults manage to hibernate here successfully. The females arrive here already mated, ready to lay their eggs in early summer, so the ones we see here in late summer and autumn are these offspring. I was delighted to see seven at once on ivy growing in the hedge on the western side of Stables Lane Park one sunny morning in late September. You may even see them into October if it’s a warm sunny morning - less likely in the afternoon since the sun by then is no longer on that spot.
Butterfly Conservation Field Guide
Although our transect season is over, you may see butterflies well into October if the weather is warm and sunny. If you do and you manage to get a photo, I’d love to see it. Please send it to me at the email address below.
The 2027 monitoring season will start in April, so we’ll be able to compare next year’s sightings with what we found this year, using exactly the same route and the same methods.
It is feared that the hot dry weather this year will cause a drop in numbers of many species next year. This is because the plant foods needed by the caterpillars (which become next year’s adults) dried up. Only by doing countrywide transect walks will we know the true impact.
If after reading this you’d like to become involved and join our team of volunteers, please email me. If you have been inspired to find out more about butterflies I can recommend this book. Not only does it tell you all you need to know about different species of butterflies, it has a section showing the eggs, the caterpillars and the chrysalises.
Janet Heath janetheath351@gmail.com
