Fireflies

I can tell you a little secret. Once you get all 10 Alchemy Skills, you'll get an opportunity. With this opportunity it will ask your sim to bring in some different things, and one of those will be insects. Now if you go into map mode, you will see different markers of the type of insects that are in the world your sim is in. I use this opportunity to find those hard to find insects. Usually if your in Moonlight Falls those very rare insects will show up around the hospital, but it will be a rare event. This is one opportunity I make sure I take my time completing, because I do like finding all those special insects.

If you have the University EP installed, there is a skill that will allow your sim to clone quite a bit of things as well. I use that to clone the hard to find ones also, especially those needed for the different elixirs.