This species parasitizes exclusively in the butterfly species Phengaris nausithous and Phengaris teleius. The imagines fly from late July to mid-September and this flight season is adapted to the presence of the larval stages of its host species (Pfeifer 2016). The females deposit their eggs on the flowers of Sanguisorba officinalis, the food plant of the two butterfly species. After hatching the larvae infest the larvae of the butterfly host that are living on the same flowers. The butterfly host is itself a parasite of ants (genus Myrmica) and after two to three weeks feeding on the Sanguisorba flowers, the butterfly larvae migrate to the ground where they are collected by ants and carried to their nests. The butterfly larvae trick the ants to feed them, and thus are mainly commensals, but frequently they also eat the larvae of the ant host, thus becoming a true parasite. The larvae of Neotypus melanocephalus do not kill the butterfly host larvae until these have been collected by ants into their nests and have pupated. In this way, they manage to overwinter together with their host larvae in the ant nests, and in the following summer the next generation of Neotypus melanocephalus ecloses and hatches from the pupal carcass of its host.