Buglife conservation officer Laura Krusin said: “The narrow-headed ant is only found at one site in England and the erratic ant is also nationally scarce, putting these species’ survival at risk.”
She said both species had seen declines in their numbers over the last 150 years, mostly because of the loss of their heathland homes.
Chris Moulton, of the Devon Wildlife Trust, said the first step would be to improve the heathland habitat in the nature reserves to secure the existing ant colonies.
He said the target was to double the number of narrow-headed ant nests from 200 to more than 400 at Chudleigh Knighton Heath.
Other heathland reserves, including those at Ideford Common and Teigngrace Meadow, would become home to both species, he added.
