It is spring on the Front Range of Colorado, which means before long the region will receive an influx of many, many moths.

The butterfly sanctuary in Mexico City’s Natural History Museum is now the host of thousands of Orizaba silkmoths. Those moths have been steadily decreasing in number in the city due to urbanization.

Two moths the size of a hand, patterned in brown and pink around four translucent sections like window panes, mate for hours ...