Parasitic wasp (Tetrastichus planipennisi). This wasp shows potential as a biological control agent against the emerald ash borer (Agrilus planipennis) beetle, an invasive species that is threatening ash tree (Fraxinus sp.) populations in Europe and North America. The female wasp lays her eggs in the larvae of the beetle. When the eggs hatch the wasp larvae feed on the beetle larvae, killing them.