I could try to find something, but that may take a while...
In the meantime, if you don't mind using cheats, you can use testingcheatsenabled true, then restrictbuildbuyinbuildings false, and buydebug on, go to Edit Town, select a lot like a park or something that matches the collectible you want to add, Buy on it, go on "sort by function", and click the "?" there. You'll find menus for insects, metals, fish, etc. Find the insect spawner you want (since it's Will O Wisp, it has a Late Night marker, so it shouldn't be hard find it) and put one, maybe two down in the neighborhood. Although not really legit, this helps if you really want it.