The Harlequin bugs are infected with the Laboulbeniales sexually-transmitted disease and can give off a nasty chemical smell.
Flying with black wings instead of red ones, the ladybirds are seeking warmth in UK properties as winter looms.
Rory Dimond, ecological contractor for nature charity Buglife, said: "The Harlequin ladybirds are an invasive species from Asia.
"They particularly like houses and outbuildings and have a habit of gathering together in suitable areas.
Major Doncaster bridge will be closed for a whole month for essential maintenance
Hosepipe ban for Doncaster as Yorkshire Water introduces drought restrictions
Doncaster man's lost watch appeal after going home with 'lass whose name he can't remember'
Man seriously ill in hospital as Doncaster city centre street cordoned off after assault
Caravan and garage deliberately set on fire in Doncaster
"The ladybirds pose no danger to humans - but large gatherings can give off a chemical smell and in centrally-heated houses they may be woken up from hibernation by the warmth and fly around the house.
"Although it is not a native species, they are now so abundant that killing them will have next to no impact and we do note advocate spraying them with pesticides.
"It is best to remove the ladybirds humanely if you can using a glass and card."
Swarms of the ladybirds were first spotted in Plymouth this week. Residents recorded strange scenes of large numbers of the bugs climbing over windows, furniture and even statues in a cemetery.