Loading data…
Synchronising catches, traps, nests and 2026 weather data…
EVOLUTION OF CATCHES
AND NESTS

Citizen catches, confirmed or neutralised nests, mean air temperature at 2 m above ground and biological reference points.

Dynamic monitoring 2026

Dynamic monitoring

Sources: Vespa Alert and weather API / IRM-KMI with Open-Meteo as fallback.

Important: the data are declarative. Catches and nests must not be added together: they describe two different types of information.
Cumulative catches
-
Total reported through citizen traps.
Catches today
-
According to today’s records.
Monitored nests
-
Confirmed + neutralised.
Mean temperature today
-
Mean daily air temperature at 2 m above ground, selected weather point.
Daily peak
-
Maximum number of catches per day.
Loading server data…

1. Activity by week

Catches, nests and mean air temperature at 2 m above ground, grouped by week. Use the switch to view by day.

Swipe horizontally to view the full chart

How to read the histogram?

By default, the graph is displayed by week. The yellow bars show the catches reported through citizen traps. The purple curve shows the moving average of catches: it smooths short-term fluctuations to make the overall trend easier to read. The black curve shows confirmed or neutralised nests. The orange curve shows the mean air temperature at 2 m above ground for the selected weather point. In weekly view, it corresponds to the average of the available daily mean temperatures for that week.

Moving average: in weekly view, each point corresponds to the average of the last three available weeks. In daily view, each point corresponds to the average of the last seven available days. This curve does not replace raw catches: it helps distinguish a real biological trend from a short-term peak caused by weather, bait renewal, the number of active traps or delayed data entry.

  • The displayed temperature is not a maximum temperature, not a feels-like temperature and not a true spatial average for the whole region.
  • The horizontal temperature lines are indicative biological reference points: they help identify periods when queens and colonies may become more active.
  • An increase in catches may also reflect more active traps or more records, not only a real increase in population.
  • Catches and nests must not be added together: they describe two different types of information.
Sources

Data sources and scientific sources

Data sources

  • Vespa Alert: declarative data from citizen traps and nest reports integrated into the platform.
  • Vespa Alert weather API / IRM-KMI: mean daily air temperature at 2 m above ground for the selected weather point.
  • Open-Meteo: weather source used as fallback when IRM/KMI data are not available.
  • In weekly view, the displayed temperature corresponds to the average of the available mean daily temperatures for that week.

Scientific sources used

  • Rome et al., work on embryonic, relocated and secondary nests of Vespa velutina.
  • Studies on the seasonal activity and predation of Vespa velutina in relation to temperature.
  • Temperature thresholds are indicative and are used to make the graphs easier to understand for the general public.