"Parisians, go home" - reads the writing on the walls in Plogoff. Messages have been scratched into cars with Paris plates, and in Plobannalec-Lesconil one car carries the scratched line "safe trip back, Parisians". In Brittany this summer smells of something that is neither salt nor iodine.

It is sharpest in the Finistere department, where the population triples in summer. Last year, between April and September, 7.4 million overnight stays were registered there. And this year the heatwave in the south of France sent another wave of tourists northwards, towards the cooler shores of Brittany and Normandy. A holiday chosen for the temperature, not for the sea.

The mayor of Plobannalec-Lesconil, Loic le Fur, condemned the scratchings: "Our town has always been and must remain an open and hospitable community." His counterpart from Penmarch, David le Ber, said something more urgent than a condemnation - that the population jumps from 5,600 to 17,000 while the roads, the car parks and the housing stay the same. In the same place, a cyclist stopped a woman who was out running to interrogate her about whether she was a local.

When the number overtakes you

French visitors account for 80 percent of overnight stays in Brittany, and 30 percent come from the Paris region. So this is not a revolt against foreigners - it is a revolt against their own compatriots, which makes the picture far more interesting. It is not a question of language or nationality but of arithmetic: infrastructure built for 5,600 people does not hold 17,000, whatever passport they carry.

From there to Ohrid, Struga or Krusevo is not a long distance. There too the number of people in August is many times what the water supply, the parking and the waste collection can handle. The difference is that in Brittany the mayors at least say the infrastructure problem out loud, instead of only counting visitor numbers.

Scratching a car is vandalism and there is no argument about that. But what sits underneath it is a different question: what does a municipality do when its population triples for three months a year, while the budget, the services and the decisions were made for the other nine?