The nature of the relationship between millipedes and O. humifusa is still largely unknown. Here we present a report on observed interactions between invasive Opuntia humifusa with native millipede species. An observation of several individuals of a millipede species feeding on O. humifusa was made. The millipede activity was observed for 3.45 minutes and photographs were recorded. Damage to live plants parts was also noted. Over 27 millipedes were observed feeding on both decaying and live plant parts on a clump of Opuntia humifusa. This observation shows that invasive O. humifusa species are interacting with native species in multiple ways. We recommend a thorough survey of the O. humifusa populations and the surrounding areas to establish more details about this feeding behavior and whether indeed it may be furthering the spread of O. humifusa in the area.