The Common Blue Butterfly.
The first of these are to be seen on the wing from the end of April onwards and will be followed by a second generation in August and September. These will be on the wing until the end of October. Eggs will be laid until the end of October on the underside of plants like clover and Common Bird’s-foot-trefoil. The caterpillars feed on these plants too and will pupate under the very same food plants. At the end of the season the last of the caterpillars will hibernate for up to ten months. They are plain green.