California pest season calendar

California's pests track its wet winters and dry summers. These windows come from the University of California Statewide IPM Program.

• Subterranean termites

  Peak window: after fall or spring rains

  Native subterranean termites tend to swarm on warm days following fall or spring rains, so watch for winged insects after the first rains.

  Source: UC Statewide IPM Program

• Drywood termites

  Peak window: summer and fall

  Drywood termite swarmers most often appear during daytime in summer and fall. They are most common in southern California and along the coast.

  Source: UC Statewide IPM Program

• Argentine ants

  Peak window: year-round, more indoors in winter

  The Argentine ant is the most common house ant in California. It often moves indoors during winter to escape flooding or cold, and sweet baits stay effective year-round.

  Source: UC Statewide IPM Program

• Formosan termites

  Peak window: late May through early August

  Where the Formosan subterranean termite is established in California, its swarming season runs from about late May through early August.

  Source: UC Statewide IPM Program

Windows are general guidance from the cited university extension and state sources, checked on August 13, 2026. Local weather and microclimate shift them, so treat these as planning ranges rather than exact dates.