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Correct answer: 4 (Nest of social wasps (Vespula vulgaris)) (Photo P.-A. Mariéthoz).

A wax scale weighs slightly less than 1 mg; approximately 1,250 scales are required to produce 1 g of wax; with 1 g of wax, bees can build about 20 cm² of comb surface on both sides.

Only the young queens fertilised in autumn survive the winter and reappear in spring to begin nest construction, lay eggs and care for the brood. The workers (sterile females) appear at the beginning of summer and then take over further nest construction and brood care. The queen lays eggs until autumn, and the colony can comprise up to 25,000 individuals, housed in an oval-shaped nest with a diameter of up to 30 cm.

The nests, built from chewed wood and “saliva”, form clearly delimited, cardboard-like walls and are located in protected, easily accessible places: wall crevices, attics, under roof structures, behind closed shutters, under gutters, in bird cages, sheds or garages, as well as in abandoned beehives.

The common wasp (Vespula vulgaris) and the European or German wasp (Vespula germanica) are the most widespread species in Switzerland. The bush wasp (Dolichovespula) also occurs; it always builds its nest outdoors, often in bushes less than 2 m above the ground. The paper wasp (Polistes) builds a small nest consisting of a single comb, without a protective envelope and attached by a stalk, often under a roof tile; this free-hanging nest is very robust, does not exceed the size of an open hand and can accommodate about 15 to 200 individuals.

Wasps are classified as pests. Nevertheless, they are important predators of undesirable insects, and the males also play a (albeit modest) role in pollination…

Main wasp species occurring in Europe:

Vespula acadica (Sladen, 1918)

Vespula atropilosa (Sladen, 1918)

Vespula austriaca (Panzer, 1799)

Vespula consobrina (Saussure)

Vespula flavopilosa (Jacobson, 1978)

Vespula germanica (Fabricius, 1793)

Vespula pensylvanica (Saussure) – invasive species

Vespula rufa (Linnaeus, 1758)

Vespula squamosa (Drury, 1773)

Vespula sulphurea (Saussure, 1854)

Vespula vidua (Saussure, 1854)

Vespula vulgaris (Linnaeus, 1758)