The UK Butterfly Monitoring Scheme operates a system of butterfly transects, which give a much better picture of how the local butterflies are doing. Each week between April and September I walk a set route near where I work and I count the number of butterflies I see within an area five metres in front of me and two and a half metres to either side.
I started my transect four years ago after noticing how many butterflies there were in a meadow where I often walk during my lunch break. I was a little disappointed when half way through the year the weather took a turn for the worse and the number of butterflies reduced accordingly. The following year it was even worse!
Last week I plotted the results of the last four years transects onto graphs and I noticed an interesting correlation between the number of butterflies and the weather at the time.
On the graphs below, week 1 is the first week in April and week 26 is the last week in September. Normally butterflies will start flying in April and peak about in the middle of May, there is a quiet period in June and then the summer species come out peaking again about the end of July.