Vespa velutina nests are built every year using substances of fibrous origin and saliva. In early spring, usually during April, the overwintered founder queens begin to construct a primary nest of the size of a tennis ball. In this first phase, the queen alone is responsible of building the nest, laying the eggs and feeding the brood. Later, with the rise of the workers, the colony grows and the nest gets bigger. Subsequently, the colony will build the secondary nest that can reach a large size and contain thousands of hornets.
The control of Vespa velutinapopulations through nest removal is complicated by the difficulty of finding all nests. The primary ones are small and difficult to find; the secondary ones, although they may reach large sizes, are often built in the middle of the vegetation and therefore are also difficult to find.
Nests can be discovered in natural areas, as well as rural and urban areas. They can be found on trees, shrubs, balconies or roofs of the houses, but also in ground holes or on the rocks. In cities and urban areas, the reports are often timely, since many eyes are around and are alarmed by the presence of hornets and their nest. In natural and rich in vegetation areas, the observations are more sporadic. This is why one of the main activities of the LIFE STOPVESPA project concerns the development of alternative techniques for locating nests, such as the entomological radar.
When a Vespa velutina’s nest is reported, it is important to remove it before the new founder queens leave the nest. In addition, the neutralization of the nests in areas frequented by people is important to prevent possible stings or accidents.