Oh yes, this beetle feeds on many 'things' of plant origin, including paper boxes if they are hungry. It was known to me to feed on a chocolate bar with almond in the past and I'm interested to know whether they wanted the nut or the chocolate. From what you described, it seems that can feed on just chocolate without the nut. Many locals like to keep beans (red, green, broad, black), herbal medicine, soup ingredients and many other kinds of health food of plant origin at home. If they were not kept in the fridge or in boxes, these tiny beetles will find their way to them eventually. Thus inside the city, there are always a large number of nuclear stocks of this beetle everywhere. It is extremely rare for any people living in Hong Kong without coming into contact with this beetle before, although usually it is the mom or domestic helper who discovers it first and throw everything away.