Iridoid glycoside sequestration by two aposematicPenstemon-feeding geometrid larvae.

The iridoid glycoside catalpol was found to be sequestered by larvae ofMeris alticola feeding onPenstemon virgatus and by larvae ofNeoterpes graefiaria which utilizeP. barbatus. The strikingly similar larval patterns of these two ennomine geometrids were previously considered to be disruptive, but predator-based Mullerian mimicry is equally likely to be involved. The cryptic adult moths generally contain only small amounts of catalpol, having left most of the bitter iridoid in the pupal case and in the meconium excreted after eclosion. OneNeoterpes female did contain considerable catalpol in the abdomen, presumably in the eggs.