One of the interesting things about Bug Collecting is finding collectors who'll buy your spare Bugs... and some will pay some quite nice prices!
So, here'a full list of the going rate for each bug on the homestead, sorted by where it's found...
Found by Searching the Rotting Log
Found by searching the Musty Shack
Moth
3'000 coins
Found by searching the Vibrant Meadow
Big Bumblebee