Gulf Fritillary nectaring on lantana. (Photo by Kathy Keatley Garvey)

It's sort of like watching the grass grow, or the paint dry, but there's much more drama.

These, as children's book author Eric Carle writes in the children's book, "The Very Hungry Caterpillars," are very hungry caterpillars.

They're famished. They're ravenous. They could eat a horse (except they don't eat horses). And that's a good thing, as Martha Stewart would say.

If they're allowed to, these caterpillars will decimate the leaves, spin cocoons and eventually turn into spectacular reddish-orange butterflies (Agraulis vanillae).

So, you're sitting there watching the caterpillars eat. And out of the shadows, something else appears.

You think you're the only ones watching them eat? Think again.