Since the "Insect of the Year" board of trustees was established in 1999 – primarily by the then director of the German Entomological Institute, Prof. Dr. Holger Dathe – this commission selects each year an insect species that should enjoy greater fame because of its special importance for the ecosystem, its particular rarity, its aesthetic value or even its "ordinariness".

The Insect of the Year is intended to bring an exemplary species (and insects in general) closer to people. Well-known entomologists, representatives of research institutions and nature conservation organisations from Germany, Austria and Switzerland together make an important and difficult decision, the choice among about one million described insect species (even if "only" about 35,000 of them occur in Germany) and select the species that is to represent the inconspicuous and yet so important "creepy-crawlies" among humans for a whole year.

Insect of the year 2025: The Sabre Wasp

Red-black legs, a slender, dark-coloured body up to 35 millimetres long with white spots and long, many-limbed antennae: the appearance of the Sabre Wasp makes it easy to distinguish it from other insect species. But the behaviour of Rhyssa persuasoria is also very special: the offspring of the insect feed on the larvae of the wood wasps and thus help to control the population of these animals, which are harmful to our forestry industry.

The female of the Sabre Wasp, which is mainly found in coniferous forests, has a slender ovipositor that exceeds the length of her body and protrudes backwards over her abdomen. The insect uses this ovipositor to lay one egg each on a wood wasp larva hidden deep in the wood. Although the presence of the larvae is not visible from the outside, the female of the Sabre Wasp chooses her egg-laying site with remarkable certainty and surprisingly recognises the trees infested by wood wasps by their smell. It does not smell the wasp larva itself, but the wood-degrading fungi it brings with it, such as the brown felt layer fungus, with the help of which the wood wasp larvae can digest the wood.

To drill the hole, which can take up to 30 minutes, the female stretches her elongated abdomen upwards and brings the ovipositor into an almost vertical position. Once the target has been reached, the elongated egg is laid on the host–the wood wasp larva. During the first three larval stages, the ectoparasitoid Sabre Wasp anchors itself in the infested larva with its long, sickle-shaped mandibles and feeds on the exuding body fluid. In the fourth larval stage, the host larva is then completely eaten. It takes around five weeks for the fully-grown larva to spin a thin cocoon in the feeding tunnel of the wood wasp larva and overwinter in it. The adults fly in forests from late spring to late summer and feed on honeydew or the sap of pine needles.

With over 23,000 species described worldwide, ichneumon wasps are the most species-rich Hymenoptera family. Due to their parasitoid lifestyle, which inevitably leads to the death of the host, they play a central role in the ecosystem by contributing naturally to the regulation of insect populations and thus maintaining the ecological balance.

In the northern hemisphere, the Sabre Wasp is a widespread ichneumon wasp species. Due to its suitability for the natural control of tree pests, it was specifically introduced in South America, New Zealand and Australia to control the introduced blue spruce wood wasp.

Rhyssa persuasoria is a prime example of the complexity and beauty of our ecosystems. It shows how even small creatures can have a big impact on nature–the Sabre Wasp makes a positive contribution to controlling wood wasps, which are problematic for the timber industry. In this way, the ‘Insect of the Year 2025’ supports forestry, reduces the need for human intervention and the use of chemical agents and can thus promote biodiversity in the long term.