雙色胡蜂 Vespa bicolor
Last April , Ho Koon Natural Education Center welcomed a new batch of resident-- Vespa bicolor. We witnessed the process from the build up to the wipe out of this community.
In our mother nature, it is not hard to spot social insects that cooperates in groups and lives in the same nest.Vespa bicolor is a species of social wasp, they are the smallest local hornet. Ground colour bright yellow , with the dorsal surface of the mesonotum (central part of the thorax) black, forming a black triangular area while their wings are clear and thinner than other hornets. It can be easily recognized due to the lack of similar species locally. It is probably the most common local hornet.
The Vespa bicolor nest was built right around the corner of the staircase. When we first discovered it , it was small at the embryo nest phrase. The embryo nest was round and the pupal cocoon caps were clearly observable (Fig 1). The nest was found by a single queen before the worker population grows and take over her job of nest expansion. As shown in the picture, the queen was completing the second layer of envelope (Fig 2).
In merely half a month's time, distinct layering of the nest could be seen (Fig 3).Vespa bicolor are built from wooden material from sources such as tree bark, rotten wood or man-made wooden stuctures , or from other plant fibres such as that found on the side of the grass stems. The wasp a small load of this material, and chews it, mixing it with her saliva, forming a paste that is applied in layers and dries into a papery pulp. The nest built from this material is light , yet solid.
Five months later, the nest expansion process completed, the mature nest was several times greater than the original embryo nest (Fig 4). Meanwhile , the fate of the nest was hung in the balance.
In late October , an intruder-- Vespa ducalis invaded the nest (Fig 5). This gate-crasher is a specialist predator on offspring of other social wasps, it soon began the raiding of the nest.
The Vespa ducalis prey on the developing pupae of Vespa bicolor (Fig 6). Under the furious attack of Vespa ducalis, the vulnerable and defenseless pupae were killed one by one, not even a single of them were spared (Fig 7). This nest of Vespa bicolor died out.