(Portland, OR) -- The Oregon Zoo is working to save the silverspot butterfly, which is listed as a threatened species. In 2019, the zoo was the first facility to breed silverspots, and this year it grew the most larvae ever. They're released at Saddle Mountain, near the coast, because that's where the early blue violet grows. That's the main food source for the butterfly. Over 21-hundred larvae were released, so the caterpillars can turn into silverspot butterflies.