They are flying termites, we had them here( Siu Lam ) for a couple of days flying around outside, at night, as they are attracted to lights.
We also had them occur like clock work this time of year in Tai Mong Tsai and Shelter Cove ( Sai Kung ) so, it's just something you get used to, while living out in these area's.
We never had any problems with them, but common sense prevails, and some simple steps can be made, which are:
•Don't leave outside porch or balcony lights on at night, if you do, draw blinds, deploy a decent sized (30cm² surface area) bug zapper and leave that running at night on the balcony or on a roof top terrace, it will attract them toward it, killing them at the same time.
•keep windows closed at night, which is a good idea in Sai Kung because it is a lot more humid there, than say where we are now, if you value your TV and any expensive electronics, I'd keep all windows shut around this ( damp ) time of year and run a dehumidifier on each floor. I had a TV dead short itself out, to never turn on ever again due to moisture that condensed on the EHT. lol.
•Purchase some 3M 3/4 inch foam tape to install around the ( exterior entry ) front door frame, to maintain a nice snug fit, as most door / frame sets are pretty sloppy with a large gap at the base of the door, which allows critters to get in under the door. Japan Store sells this.
•If you are hell bent on having windows open, have fly wire screens installed on the windows that you are likely to open most.
If you remain vigilant, you'll be fine. Remember it will only be for a few days, we had them here 3 days ago, and there weren't any last night.
No big deal... Wait till you get your first rat snake coiled up on your front door mat, or discover that rats have eaten every square inch of engine bay sound insulation ( Mercedes Benz foam rubber they adore) of your car, not to mention they have a fond taste for Italian automotive heater hoses too .
Lots of cool discoveries out in the NT, its what makes this place great, and a lot more pro's than cons.
You'll get used to the local fauna, good luck
.