One of our familiar butterfly species is rapidly disappearing from Hertfordshire, experts have warned.

Surveys have shown that, in just three years, the small tortoiseshell (aglais urticae) has declined by 90 per cent in Herts and Middlesex.

Malcolm Hull, chair of the Hertfordshire and Middlesex branch of Butterfly Conservation, said: "The fall in small tortoiseshells has been alarming. It was one of our most common garden butterflies, but this year it’s almost vanished.

"A few years back I counted 127 individual small tortoiseshells at Folly Lane Allotments in St Albans in just one hour. In 2024 I’ve seen just one in the whole of Hertfordshire all year."

Across both counties, just 47 individual butterflies have been reported to the branch this year in UK Butterfly Monitoring Scheme surveys - compared to 486 in 2022 and 104 last year.

Malcolm added: "Small tortoiseshells over-winter as adults and emerge from hibernation in early spring.

"I’ve been lucky enough to have them using my garden shed to roost in. Usually I get about 20 each winter.

"Last year there were just four and this year there are none."

Branch recorder Andrew Wood said: "The caterpillar webs on the top of stinging nettles used to be easy to find, this year we have had no reports, which does not bode well for next year."

A few weeks ago, Butterfly Conservation revealed the results of its annual national summer Big Butterfly Count - the worst in its 14-year history.

On average, participants spotted just seven butterflies in each 15-minute count - half the 2023 average score of 14.

The latest results showed that 2024 was the worst summer on record for seven species, including the small tortoiseshell.

Cold and wet weather in spring is partly to blame, as well as long-term factors such as agricultural pesticides and loss of habitats.

The charity has launched a petition at https://butterfly-conservation.org/, calling on the government to declare a nature emergency and to ban harmful neonicotinoids pesticides.

Although these chemicals are banned across the EU, and from most British farming, they have been used in Hertfordshire fields this year under a UK government exception for sugar beet.