The high temperature and humidity of the rainy season (typically June–July) create near-perfect environmental conditions for the outbreak of multiple pests — this is the most severe period for pest problems of the year in southern China and the middle-lower Yangtze region.
Mosquitoes — continuous rainfall creates countless tiny standing water containers in plant pot saucers, scrap tires, and clogged drainage systems.
At 25–30 °C, the mosquito generation cycle takes only 7–10 days — populations can multiply dozens of times within two weeks after a heavy rain.
Termites — termite swarming usually occurs on a sultry evening after rain during the rainy season; high soil moisture makes it easier for termites to excavate mud tubes and engage in foraging activity.
Cockroaches — relative humidity above 70% is the optimal humidity range for cockroach reproduction; the sustained high humidity of the rainy season brings cockroach egg case hatch rates and nymph survival rates to their annual peak.
Booklice and silverfish — pests that feed on mold proliferate massively during the rainy season; mold growth on walls, inside wardrobes, and on book surfaces provides them with an abundant food supply.
Control strategy: The continuous operation of dehumidifiers and air conditioners is the most effective way to keep indoor humidity in the 50–60% range — this alone can significantly suppress booklice, silverfish, and dust mites.
The core of pest prevention during the rainy season comes down to two words — dehumidify.