Several outer hulls keep the nest climate constant. In July and August, when the number of workers reached its maximum with approx. The queens mate and search for hidden places for winter. Meanwhile, the colony dies out, the old queen doesn't lay eggs anymore and dies. The empty nest rottens quickly in autumn and winter.
Hornets communicate mainly with pheromones.
They alarm each other with Isoamylactate and they seem to lay traces to their hive. There is also a pheromone, produced by the larva, which causes the adults to warm the cocoons. Other pheromones are not known yet. Both species are hunters. But Hornets also hunt wasps and restrict their population growth.