In recent weeks, some Hong Kong people's complaints about mainland property buyers, mainland mothers and mainland tourists on the MTR have become unpleasant, even vicious.
It is understandable that some people are bitter about unaffordable home prices in Hong Kong as mainland investors buy flats here and leave them empty. The same goes for resentment at pregnant mainlanders putting our hospitals under strain. Perhaps a few mainland visitors do break some local rules, and it is easy to see why Dolce & Gabbana made people angry a few weeks ago.
But how did it get to the stage where we have hate-filled language about 'locusts'? We can only hope for the sake of Hong Kong's reputation that this outbreak of insults and hostility will soon pass. Even so, the potential for future friction clearly exists.
It seems to me that this is a clash on several levels. On the surface, it is about resources, and our leaders need to take this seriously. There are genuine problems, and mainlanders are unfairly and damagingly being used as scapegoats as a result.
Policymakers miscalculated the effect of large-scale tourism from the mainland. The boost to our retail sector has been immense, but the government failed to anticipate how the extra visitors would increase demand for various resources. Ideally, officials should find ways to reduce competition from mainlanders for space and services. If necessary, they should pledge to provide whatever land, funds and manpower are needed to restore home affordability and maternity service capacity to what they would be without the 'mainlander effect'.
But why have some Hong Kong people found it so easy to take out their frustration on mainlanders? Mainlanders mean us no harm. They buy milk powder here because they are afraid that the product back home is tainted and will harm their children. Some want to give birth here to help give their children an advantage in life. They buy luxury goods here because of the dependability and cheaper price. Wouldn't any of us do these things in their position?
Part of the problem, I think, is that the 'integration' we heard so much about in past years is happening far more rapidly than anyone expected, and in ways we did not anticipate. 'One country, two systems' guarantees Hong Kong's very different institutions and way of life, but it doesn't freeze economies or cultures in time.
For example, cross-border marriages are no longer only a grass-roots phenomenon, and the resulting divided families are discontent and determined that their children should be born here. Things like the rise of a mainland middle class and mainland predominance on our stock exchange have come as a shock. The new global prominence of China's economy and the uncertainty about its direction leave some in Hong Kong feeling the city is reduced in importance - even if it is not.
Meanwhile, we hear contradictory messages. The mainland is a great opportunity for us, or it poses a competitive threat. Hong Kong is Asia's world city because of freedoms and institutions not found on the mainland, yet we need national education to show us how successful China is. Many of us are relaxed, even fascinated, by these contrasts and the dynamic changes, but it is easy to see why some are confused or even fearful.
Finally, I wonder if there is some shame and snobbery at work. Are mainlanders squatting on the floor in malls or eating on trains evil? When Hong Kong people started to move to Vancouver, the local Canadians complained about the newcomers' behaviour. Young Hong Kong people today are only a couple of generations away from poor mainlanders. Their grandparents possibly spat and helped their children go to the toilet in the fields or in village gutters.
Could it be that when Hong Kong people, proud and convinced they are superior, look at some less-sophisticated mainlanders, they see something they do not want to be reminded of?
Bernard Chan is a former member of the executive and legislative councils