Actinote caterpillar

Thanks Keith! That was exactly the comment I expected from you ;-)... Nature do not create such spines just for fun, that would cost too much effort. As you pointed out there are too possibilities: indeed poisenous (sometimes extremely poisenous or nasty...) spikes or mimicrying being poisenous. They are both very effective measures to avoid being touched. And hand-ling or being fed are completely different things... Interesting is the fact, that Actinote is usually feeding on Asteraceae and not Passifloracae as you might think if you read about toxic caterpillar. It is indeed depending on the diet of the caterpillar if the later butterfly (mostly Heliconinae) will be unpalatable due to accumulation of toxic alcaloids. And even more interesting is the mechanisms of avoiding cannibalism by different caterpillars. So, some Heliconians do check the Passiflora if there are already some eggs on it. If yes, she will go to the next one. The passiflora itself can produce some egg-like looking points for mimicrying "already occupied". So with this measure it will avoid being destroyed by a caterpillar. It can even attrack some ants and other insects to feed on the already deposited eggs... Very sophisticated and interesting...
Looking at the above caterpillar... I would never try to touch it ;-)... So you must have a very experienced hand as you have the experience as expert in caties...

Being not a scientist, I can rely only in my personal experience. I've seen some consequences of the contact with caterpillars, including a young guy who had one on his belly. The poor guy cried out for a whole night (odd enough, the only thing that helped him was a home made red pepper sauce, provided by an old neighbor woman). From then on, I carefully avoided contact with ANY spiked caterpillar. So, you're right Keith, to LOOK like something dangerous is a clever investment (as false coral snakes also learned).

I have purposely handled many spiny nymphalid caterpillars over the years with no ill consequences (unlike some moth larvae). But the mere fact that you, along with birds and other vertebrate predators, "assume" they are painful to touch proves the effectiveness of such an appearance.

Nasty guys, indeed!