A team from the University of Cambridge and a wildlife trust tested 2,000 insects in Bedfordshire.
They are investigating how effectively species can warm or cool themselves, which could help the insects cope with a warming climate.
The full results will be published this summer.
Twenty-five researchers and volunteers recorded information about more than 12,000 butterflies at four reserves owned by the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire, taking the temperature of 2,073 of them.
The team looked at how much certain butterfly species can change their body temperature compared to the air temperature.Image copyright Andrew Bladon Image caption
Dr Andrew Bladon, from the university's insect ecology group, said butterflies had well-known habits, such as basking in the sun with their wings open to warm up, but effectiveness varied between species.
"That will have consequences in how active they are able to be. On a cold day, species good at heating themselves will be active earlier - feeding, mating and defending their territory," he said.