# European caterpillar infestations

> Developing situation record from CLSTR: https://clstr.news/situations/european-caterpillar-infestations
> Updated: 2026-10-22T07:44:21.000Z. Sources: 7. Developments: 2.

In mid-October 2026, a massive invasion of Euclidia glyphica caterpillars caused significant agricultural damage in the Sargans region of St. Gallen, Switzerland. The infestation stripped approximately 50 hectares of meadows bare, representing ten percent of the region’s total meadow area. Officials attributed the surge to warm weather allowing the heat-loving moths to migrate from Southern Europe, noting that the insects currently lack sufficient natural predators in the area.

By late October, a similar phenomenon was reported in northeastern Italy near Vicenza. In this region, an invasion of Mythimna unipuncta caterpillars, also driven by exceptionally high temperatures, caused damage to permanent meadows along the Brenta river. Local officials reported that the species is spreading rapidly from Nove to Quinto, necessitating the complete reseeding of affected meadows. Experts in Italy have advised against using insecticides to manage the outbreak.

## Claims

- Mythimna unipuncta caterpillars are causing damage to meadows northeast of Vicenza, Italy. (reported by 2 sources)
- The caterpillar population surge is attributed to exceptionally high temperatures for the season. (reported by 2 sources)
- Mythimna unipuncta females can lay more than 1,000 eggs. (reported by 2 sources)
- The caterpillars have damaged permanent meadows on the right bank of the Brenta river. (reported by 2 sources)
- Experts have rejected the use of insecticides to combat the invasion. (reported by 2 sources)
- A meeting was held at the Quinto Vicentino town hall involving local mayors and the Brenta water management association. (reported by 2 sources)

## Timeline

### 2026-10-22: Caterpillar invasion causes damage in northeastern Italy

An unusual surge in Mythimna unipuncta caterpillars is causing extensive damage to meadows in the region northeast of Vicenza, Italy, following an unseasonably warm period.

3 sources. https://clstr.news/cluster/caterpillar-invasion-causes-damage-in-northeastern-italy

### 2026-10-16: St. Gallen caterpillar invasion destroys 50 hectares of meadows

Millions of Euclidia glyphica caterpillars have stripped 50 hectares of meadows bare in St. Gallen, Switzerland, causing significant agricultural damage and prompting investigations into control measures.

4 sources. https://clstr.news/cluster/st-gallen-caterpillar-invasion-destroys-50-hectares-of-meadows

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Cite as: European caterpillar infestations. CLSTR, https://clstr.news/situations/european-caterpillar-infestations