Dalceridae are commonly referred to as “slug” caterpillars because of their impressively slimy appearance. If I’m honest, I think the nickname is a little unfair. Slugs are unanimously considered to be ugly, whereas I think you’ll agree that these Dalceridae caterpillars, although gooey, are pretty amazing to look at.
The family Dalceridae (part of the Superfamily Zygaenoidea) are comprised of 84 known species, mostly inhabiting the Neotropic ecozone. For those unfamiliar with the nomenclature of the ecozones, I looked it up so you wouldn’t have to.
The Neotropic ecozone includes South and Central America, the Mexican lowlands, the Caribbean islands, and southern Florida.
When the Dalceridae caterpillars change from their unearthly slime outfits into their adult moth garb, the adults that appear are particularly hairy. In general you would expect the adult, winged form, to be more attractive, but in the case of Dalceridae and it’s cousins, Limacodidae and Megalopygidae, this is not the case at all; quite the reverse, the adult is relatively dowdy.
Interestingly, science hasn’t worked out the reasoning behind the caterpillar’s multicoloured coat yet.Dalceridae appear to fear no birds and make no attempt to hide or blend into their surroundings whatsoever. But so far, the Dalceridae don’t appear to be poisonous or be able to bite or sting.
As for the odd cone shapes spread across the slug caterpillars, their function may have been revealed. It appears that they work in the same way as a lizard’s tail. If the slime cones are pulled, even gently, they break off, possibly affording the caterpillar vital microseconds in which to take evasive action.
In one experiment on Dalceridae, scientists released a few ants (Camponotus floridanus) in the vicinity of the Dalceridae youths and watched the attack.
Most of the ants gave the caterpillars an exploratory prod with their antenna and decided against snacking on the caterpillars. Some of the ants did go in for the kill, but it seemed they were not at all fond of the sticky cone of goo messing up their pincers. So even the ants that did decide to attack were deterred and recoiled busily cleaning their mandibles.
But like I say, the goop doesn’t appear to be toxic, it seems that its unpleasant consistency is enough to put off any would-be attackers.
So, in conclusion, Dalceridae are wrongly accused of being slug-like, and should be considered the entomological equivalent of tapioca.
