The use of nicotine-like pesticides may be contributing to the decline of butterflies in the UK, research by the University of Stirling has revealed.
Previous studies have shown that neonicotinoid chemicals appear to be harming bees, birds and other wildlife.
The university said this was the first evidence of a negative impact on butterflies.
The study, published in the journal PeerJ, used date gathered by volunteers at over 1,000 sites in the UK.
Scientists at Sussex University were also involved in the research, which was supported by Butterfly Conservation and the Centre for Ecology and Hydrology.
The research team found that the chemicals could be absorbed by wildflowers growing in field margins, many of which are a nectar source for butterflies and food-plants for their caterpillars.
Stirling university ecologist Dr Andre Gilburn, who led the research team, said: "Our study not only identifies a worrying link between the use of neonicotinoids and declines in butterflies, but also suggests that the strength of their impact on many species could be huge."
The study found that 15 species showed a decline in population linked to neonicotinoid use, including the small tortoiseshell, small skipper and wall species.
Neonicotinoid pesticised were introduced in the mid-1990s as a replacement for older chemicals.
They are what is known as a "systematic insecticide", meaning that they are absorbed into every cell in a plant, which makes all parts poisonous to pests.
They were banned for use on flowering crops by the EU in 2013 and the UK government partially lifted the ban in 2015 for use on oilseed rape in certain regions.
Dr Tom Brereton, head of monitoring at Butterfly Conservation, said: "We are extremely concerned with the findings of the study and are calling for urgent research to see whether the correlations we found are caused by neonicotinoid use, or some other aspect of intensive farming.
"Widespread butterflies have declined by 58% on farmland in England over the last 10 years giving concern for the general health of the countryside and for these and other insects in particular."
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