14 July, 2021
Cuckoo Wasp Chrysis viridula – parasitising Spiny Mason Wasp Odynerus spinipes
Recent forestry woodland work had resulted in compacted banks of exposed soil due to heavy vehicle traffic removing diseased Ash trees. One such spot created the ideal environment for a small colony of Odynerus Wasps, thought to be Odynerus spinipes, the Spiny Mason Wasp. These wasps excavate nest chambers in the hardened soil, creating a distinctive chimney of worked soil between 10-30 mm in height at the entrance.
The Spiny Mason Wasp is often parasitised by another wasp – Chrysis viridula, one of a group of specialized wasps known as Cuckoo Wasps. Several of these fascinating insects were observed moving rapidly among the chimneys of the Spiny Mason Wasp colony, often disappearing into a chimney for a few moments, no doubt to deposit their eggs in the chambers.
On occasions, the Spiny Mason Wasp would return to its chimney whilst the Cuckoo Wasp was still in the chamber. It was interesting to watch the skirmish that followed with the much larger Mason Wasp struggling to evict the smaller wasp and apparently attempting to sting the smaller insect. It seems that the Cuckoo Wasp has a hardened chitin skin that can provide protection from stings, and it is also able to roll itself into a ball when attacked, thereby further reducing the chance of being stung.
Spiny Mason Wasp – Odynerus spinipes
Photograph by – Steve Horton