Finding the Lorpen Butterfly
Lorpen as well as quite a few other kinds appear in the wilds. Unlike the most these can appear anywhere, but with significantly lower chance.
As for example, if you unlocked an area with golden butterflies then you can craft a metal platform above the pillar at the entrance to that place and stand in a middle for a while. Beside quite a lot of Serena Larva you’ll find both Golden and Lorpen there.
Not that you have to build a platform that up high, but looking for larva in the grass and debris around is quite troublesome.