Thought I'd pass along this interesting summary in Science concerning the invasive wasp, Vespuia vulgaris, and its interaction with the native New Zealand ant, Prolasius advenus. The actual paper is in Biology Letters but I can only get you to the abstract: A novel interference behaviour: invasive wasps remove ants from resources and drop them from a height by Julien Grangier and Philip J. Lester.

