The short answer
Hong Kong's pest problems broadly track the weather: the spring damp period (roughly February to April) is peak season for booklice and mould; termites generally swarm from April to July; mosquitoes are active roughly March to November, with May to September the busiest stretch; wasp nests need distance and care whenever they are found; bed bugs are a year-round risk, with luggage-related infestations rising during heavy-travel periods; and cockroaches, rodents and ants are a constant, year-round fight. The best time to get ahead of almost anything is before its peak — the month-by-month breakdown below covers each one.
The year at a glance
Jan — prep month: check dehumidifiers and window seals before the spring damp arrives; check luggage after year-end travel. Booklice handbook
Feb–Mar — booklice, mould (spring damp): humidity monitor, dehumidify, clean mould. Booklice handbook, Humidity tracker
Apr–May — termite swarming begins + rising mosquito activity: lights off, windows closed against swarming termites; clear standing water. Termite signs, Mosquito index tracker
Jun–Jul — peak mosquito season, termite swarming tapers off, cockroaches active: weekly check of standing-water sources; bait deployment. Mosquito control, Cockroach DIY vs professional
Aug–Oct — look for standing water and signs of nest activity from a distance; do not attempt to remove a wasp nest yourself. Wasp nest removal
Oct–Nov — year-end travel season: bed bugs travel home in luggage, mosquito season tapering. Build the luggage-check habit; hot-wash on return from trips. How bed bugs get in
Dec — year-end clean-up: seal gaps, fix window seals, clear clutter that hides pests. Rats entering the home
Year-round — cockroaches, rodents, ants, fleas: keep food sealed, drain covers on, take out rubbish daily (each pest hub page).
Months are a general pattern that shifts year to year with the weather — for current mosquito conditions, see our monthly-updated mosquito index tracker; for humidity, see the humidity tracker.
Why "get ahead of it" matters
The cost of dealing with any pest problem tracks almost exactly with how late you catch it: a small wasp nest costs less than a large one; controlling humidity before the spring damp costs less than removing mould and booklice afterwards; and doing the right three things on a termite swarming night — lights off, windows closed, checking the next morning — can save you a full inspection bill. The point of a calendar isn't to alarm you; it's to give you one small prevention task, two to four weeks ahead of each peak.