From a peppermint Pericopinae. I recorded this video on-site in northern Costa Rica a few years ago. When I reached down to pick up this moth, it was hard to avoid noticing the behavior. The moth, Chetone angulosa (Noctuidae: Pericopinae) ((used to be Arctiidae)), has a common defensive mechanism for this group – they excrete hemolymph to deter would-be attackers. Lots of moths do this, but I have never seen it so spectacularly displayed. If you listen carefully you can hear the hissing sound as the fluid is pumped form the body. What was most impressive is how strongly it smelled of peppermint… strongly enough that I just had to give it a go. Sadly, it didn’t taste as advertised. While it wasn’t excruciating, the most noticeable effect was an abrupt numbness that lasted for a several minutes. Pretty potent stuff, and I can imagine the effect on a small bird or mammal might be far less amusing.
It seems like biologists have a funny habit of tasting their subjects. I recently sat in on a herpetology talk regarding poison-dart frogs. On a slight tangent, did you know that the coloration of these famously aposematic frogs has NEVER been tested until recently? The fact that they were poisonous is well known, but no one ever took the time to see if their colors actually fit a true aposematic model, that is – do they really deter predators in the wild? Turns out not surprisingly, yes, they do. But it’s nice to actually have quantitate data to support this long held assertion. Back to tasting – a well known herper test is to give the frog or toad a lick. While this can actually help to identify the species of herp, it more likely seems to be an amusing side effect of long hours in the field. Not being a herper I can’t recall the name or group this applied to; but a famous paper went into great depths to describe the tastes, potent effect and the potential dangers associated with each licked toad species (this was a legit taxonomic review).
The only example for useful tasting in insects that I can think of right now is for two strikingly similar butterflies- Papilio thoas/cresphontes. I believe thoas has a sweet flowery smell when you catch it fresh (yes, not a taste… but close), however I’ve never seen this published or tested it myself, so it may be apocryphal. It is however well known that many butterflies smell strongly of their hostplant: such as Speyeria coronis smelling of Apocynum (strong vegetable odor). Lots of room for further investigation here. But without a doubt a biologist uses all five of his senses whenever he can.