Knowing how to identify Asian hornet nests

Key points to remember

• The Asian hornet adapts to many nesting sites
• Secondary nests are often high up and difficult to see
• Their architecture is robust and scalable.
• Early detection facilitates effective and safe intervention

The main nesting sites

In the trees

Trees are the most common nesting site for secondary nests of Asian hornets.

• The nests are often located several meters high, sometimes more than 15 or 20 meters.
• They are located at the tips of branches or in the foliage, making them difficult to detect.
• The dense foliage effectively conceals the nests during the summer.

The nests often become visible in the fall, when the leaves fall.

Hedges and vegetated areas

Thick hedges, thickets, brambles and poorly maintained areas can also accommodate nests, especially when the height and density of vegetation offer good protection.

• These nests are generally lower than those located in trees
• They present an increased risk to humans because they are at passage height

Buildings and dwellings

The Asian hornet readily establishes itself in the immediate vicinity of inhabited areas. Nests can be found in:

• attics and lofts
• garages and garden sheds
• under the eaves
• in hollow walls or unused chimneys

These locations are particularly prized for primary nests, as they offer warmth, stability, and protection.

Barns and farm buildings

Barns, agricultural sheds and rarely used buildings are ideal sites for Asian hornets.

• The ceiling height allows for the development of large nests.
• Minimal human disturbance promotes the colony's long-term establishment.

Architecture and structure of an Asian hornet nest

The Asian hornet's nest is a complex structure, built from chewed wood fibers mixed with saliva, giving it a cardboard-like appearance.

A construction in successive layers

• The nest is composed of several overlapping concentric layers.
• These layers provide good thermal insulation and protection against the elements.

Nest size and development

• A primary nest typically measures 10 to 15 cm in diameter.
• A secondary nest can reach 80 cm to 1 meter in height
• Its weight can exceed several kilos by the end of the season

Internal organization

Inside the nest:

• Several cell trays are used for raising larvae.
• Each cell contains an egg, then a larva and a pupa.
• A mature colony can contain several thousand cells.

The entrance to the nest is located on the side, which makes it possible to distinguish the nest of the Asian hornet from that of the European hornet.