Data

Seasonality of indoor spider encounters

Indoor sightings of large synanthropic spiders peak in late summer and early autumn in most US regions, driven primarily by male search activity rather than population growth.

Pattern

Aggregated citizen-science observation data show a sharp late-August through October rise in indoor encounter reports for Eratigena, Tegenaria, and large Steatoda. The rise reverses sharply by mid-November.

References

  1. [1]SpiderSpotter / citizen-science arachnology programs - Royal Belgian Institute of Natural Sciences. Accessed June 2026.

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