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Termite Swarms After Rain — Why It Happens and What to Do
Both drywood and subterranean termites commonly swarm in Southern California in the days following warm rain events. If you've seen flying termites after recent rain, here's what it means.
Rain triggers termite swarming through a combination of increased soil moisture (subterranean) and warm post-rain temperatures that signal ideal colony expansion conditions. Southern California's rainy season — roughly November through April — coincides with peak subterranean swarming activity.
Subterranean swarmers emerging after rain may appear around the yard, near foundation areas, or around utility entry points. Drywood swarmers are less affected by rain specifically but will swarm during warm periods spring through fall.
Post-rain swarmers emerging from soil around the foundation strongly suggest active subterranean termites. This is an urgent situation — soil moisture following rain makes it an ideal time to apply Termidor soil treatment while conditions favor deep penetration into the treatment zone.
Don't confuse termite swarmers with flying ants. Termite swarmers: equal-length wings, uniform body width, straight antennae. Flying ants: unequal wings, pinched waist, bent antennae. Both appear after rain — only one is a termite.
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Frequently Asked Questions
Is post-rain swarming a sign of a new infestation?
Post-rain swarmers mean a mature colony (typically 3–5 years old) is present and sending out reproductives. The infestation is not new — the swarm is evidence that an existing colony has been established for years.
What should I do immediately after seeing a post-rain swarm?
Document where you see the swarmers — inside or outside, near soil or near wood structures. Collect a few specimens. Then schedule an inspection promptly. The days following a swarm event are the best time to assess and treat.
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