New host wasps attacked by Mirothrips arbiter (Thysanoptera: Phlaeothripidae) are recorded and their possible feeding on fungi and mites in colonies of Polistes melanosoma and Polistes ferreri is evaluated. No predation events on mites or fungal ingestion were observed, indicating that these thrips only use wasp eggs as food. Thrips do not parasitize wasps’ bodies, they only live at the expense of their colonies, where they find food and shelter. However, as these insects feed on the immature stages of the wasps, it is possible that they cause or accelerate colony decline. Given this, we can say that the ecological relationship between thrips and social wasps is that of social parasitism, that is, thrips are parasites of wasps colonies, they depend directly on them for their survival and cause damage to them. From our findings, the number of host wasp species of this thrips rose to five, all belonging to the Polistinae subfamily.