I’m not a natural Lepidopterist – over recent years I’ve come to appreciate some of the less aesthetically appealling taxa and their fascinating ecology, so find beautiful butterflies a bit too ostentatiously pretty for my tastes! Moths, on the other hand, I find rather good fun – often (though by no means always) the adults are dull shades of greyish brown (though the wing patterns can often be wonderful), while the caterpillars can be bizarre to the point of otherworldly.
Hairy, spiky, multicoloured, mimicking something else or perhaps just resembling a fantastical piece of conceptual artwork, moth caterpillars can provide endless variety for a globetrotting ecologist.
One particularly memorable encounter in recent years for me has been with the caterpillar of a Caribbean species of cup moth (Lepidoptera: Limacodidae), probably a Phobetron species. We came across it in Trinidad and its appearance was so utterly weird it took me a minute to figure out what I was actually looking at. It was brown and hairy, with six to eight false “legs” and some whorls of hair that almost looked like suckers, and was crawling slowly across a small tree. I decided it would be inadvisable to touch it (which, as it turned out, was probably a good decision on my part, as various sources claim their spines can be irritant/toxic 1).
(Clicking links to a video of the creature walking down a tree)
I assume it’s trying at least half-heartedly for tarantula mimicry – if I was a hungry bird I’d definitely think twice.
Other closely related species can be even odder, with up to nine pairs of legs.
Their ecology is actually nothing particular special: they munch on various ornamental and horticultural plants, especially small trees. Although the coolest seem to come from the Americas, the family is also present in Asia, where one species is a pest of coconut trees as well as coffee, cocoa and oil palm2. Although there was once a bit of an outbreak of them3 in Panama following a rather severe drought, which makes for some pretty interesting mental images.
The diversity of Limacodidae caterpillars is pretty mind-blowing – lurid colours, hairy spines at strange angles. I suppose they remind me of what happens when a toddler gets to play in a particularly well-appointed dressing-up box!
Really, who needs sci-fi when you have Limacodidae?
With a caterpillar like that, what must the adult look like? Well, as is frequently the case with moths, this most wondrous caterpillar pupates into medium-sized, hairy but by comparison relatively uncharismatic adult moth. It has been suggested that the hag moth (Phobetron pithecium) is a bee-mimic, which I suppose is possible, though it’s perhaps not the most convincing I’ve ever seen!
Virginia Tech/Virginia State have produced a nice little factsheet on the North American species.
1Murphy, S. M., Leahy, S. M., Williams, L. S., & Lill, J. T. (2010). Stinging spines protect slug caterpillars (Limacodidae) from multiple generalist predators. Behavioral Ecology, 21(1), 153-160.
2Chenon, R. (1982). Latoia (Parasa) lepida (Cramer) Lepidoptera Limacodidae, a coconut pest in Indonesia. Oléagineux, 37(4), 177-183.
3Van Bael, S. A., Aiello, A., Valderrama, A., Medianero, E., Samaniego, M., & Wright, S. J. (2004). General herbivore outbreak following an El Nino-related drought in a lowland Panamanian forest. Journal of Tropical Ecology, 20(06), 625-633.
sarahejarnold 
What a fascinating creature! I thought the picture was strange enough, but the video was even more interesting. At first I imagined it to be a grouping of caterpillars but it’s just one individual!
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It is indeed a fantastic little beast. The movement is quite odd – certainly more sluglike than spiderlike. At the time I ended up easing it gently away from the leaf in order to see its underside, at which point it became somewhat clearer that it was a type of caterpillar… Some months later I saw what is presumably a related species that was white with almost lacelike structures coming out. Sadly the photos were rubbish or I’d have shared them too.
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