In the past, it was thought that termite colonies could not establish in mulch. The following is a short article that shows that this might not be the case.
Termites in Mulch?
Termites have underground colonies and feed on wood, and may be found in mulch. In the past, most entomologists agreed that any termites brought into a site via mulch were workers and not reproductives (queens), and therefore there was little risk of a new colony developing. However, new research shows that if the mulch contains enough white worker termites, and they are given access to soil, these termites do have the ability to develop into secondary reproductives and establish a new colony! In light of this, bagged mulch should be stored on pallets off the ground, so termites cannot gain access to the mulch. Termites need ground to wood contact to easily gain access to the wood food source from their underground colony. Likewise, piles of mulch should not be stored directly on the ground. Keep bags of mulch in the sun as well, since termites should not survive high temperatures that build up during the day. Also beware of adding too much mulch to the landscape (2 to 3 inches is plenty).
Information from Steven K. Rettke in the October 10, 2002 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2002/ln1010.pdf