We have Penny Royal as a ground cover. Until recently it was doing
incredibly well. A few months ago we noticed one of the plants had been
stripped entirely of it's leaves. For a while after that nothing more
happened.

Recently whatever it was returned and went a little crazy. Most of the
plants are now stripped to their stalks. We've spent hours looking over
the plants for possible culprits but have found nothing that explains
it. A single caterpillar here, or beetle there but nothing in the kind
of numbers I'd expect to do this kind of damage so quickly.

I started looking on the net for answers. It seems that Penny Royal is
a popular pest repellent which leaves me further perplexed. If it's so
good at repelling insects what could possibly be eating it?

Assuming we can identify it the next question is what can we do to
control it? We're against anything that might negatively affect the
local insect, plant or animal life. And we're even happy to cede a
percentage of the plants to whatever it is. But this total devastation
is hard to accept.

Anyone got any ideas?

James