Two males, one female: triplet-style mating behaviour in the Darwin wasp Xorides ater (Gravenhorst, 1829) (Hymenoptera, Ichneumonidae, Xoridinae) in the Swiss Alps

The Darwin wasp Xorides ater is a solitary idiobiont ectoparasitoid of wood-boring beetle larvae. It occurs across the Palaearctic, and in Switzerland seems to be restricted areas above 980 m altitude. Very little known about its biology behaviour. We here report three separate instances female X. mating simultaneously with two males, observed on same occasion Picea abies woodpile near Lenk, Switzerland. Only copulae that involved one male were at time, which might indicate this mode rather common . illustrate our observations photo video material compare it behaviour from other species wasps.