Hello doctoroe,
I am new to GardenBanter.co.uk and suspect navigating around here will become easier. I am sure by now you have found the name of this bug that you mentioned in a post dated in July of 2008. But I will tell you my experience with them.
I too, live in NC, southeastern NC, the sandhills. I never noticed this type of bug until I started growing Hoyas, stapelias, huernias and any other Ascleiads on a larger scale this year. Those are all plants in the milkweed family. The bug in question, for lack of a scientific name, is called milkweed bug. They are destructive if not plucked as soon as you notice them, but easily stomped. No need of pesticides.
Here, you will find them around early to mid September. This is when the Monarch butterfly, as it makes it's journey west to California comes to my neck of the woods. Anything in the milkweed family is susceptible to this predator who feeds on the nectar produced by milkweed type plants, mainly the flora found in meadows.

Migrating Monarch Butterflies have an awful long journey and they stop in any field on the way where milkweed flourishes because they get the highest concerntration of sugars for engery and nourishment for the long trip from milkweed. For brevity I would say 'google it' which plants that would entail.

The milkweed bugs are nothing more than opportunists that find their favorite treat where they can get it. Be advised they are destructive to your asclepiad plants.

We should all try and grow some variety of plant that the Monarch love because they, like many other things we have taken for granted are in danger of becoming extinct.

Kind Regards,
Katherine