HM Queen Paola has a golden snake bracelet with blue stones in it. Also a diamond & aquamarine butterfly. I think I have once seen her wearing also a diamond dragonfly. Not sure about the last one.
HM Queen Fabiola has a diamond & golden? bee/wasp.
HM Queen Mathilde has diamond bird (not really insect or amfibians or snake)
HRH Princess Astrid wore once a very big diamond snake collier.