A POLITICAL brain teaser: which party in which country has promised “punitive measures” against illegal immigration, has threatened to disenfranchise people who arrived half a century ago and has told migrants to “be prepared with their bags packed”?

The answer is not the National Front of France, the United Kingdom Independence Party, Jobbik of Hungary or indeed any other insurgent political party in the West. It is the ruling Bharatiya Janata Party of India. The BJP and its leader, Narendra Modi, rail against immigrants from Bangladesh, of whom there might well be more in India than there are Mexicans in America (see article). This nativist ranting is evidence of a nasty strain of developing-world demagoguery.

Pakistan is currently trying to evict hundreds of thousands of Afghan immigrants, some of whom have lived in the country for decades. Gabon and Equatorial Guinea are expelling migrants from central Africa. Mexico, which complains bitterly (and rightly) about the treatment of its people in America, does far too little to prevent the mass kidnapping and murder of immigrants from Central America.

All political leaders, even dictators, must take some note of how their people feel, and the citizens of poor and middle-income countries are often no better disposed to immigrants than are voters in the rich world. Besides, a government that threatens to shut its refugee camps or uproot millions of migrant workers from their homes might be able to extort some money out of Western donors. But the treatment meted out to immigrants in developing countries is nonetheless dismal—futile, illiberal and economically ruinous.

Even in rich countries, where most workers have formal jobs and are known to the authorities, illegal immigrants are hard to catch. In poorer countries, where the state is weak and almost everybody works informally, it is close to impossible. National boundaries tend to be porous. At about 4,100km (2,500 miles), the border between Bangladesh and India is longer than the border between Mexico and the United States. It is so thinly policed that cattle can be trafficked across it.

Like migrants everywhere, the people who cross into developing countries are nearly always trying to better themselves and their families. Unlike the migrants who make it to the West and the Gulf states, they are frequently very poor indeed. When America and Europe tighten their borders, middle-class Indians and Nigerians lose out; when India and Nigeria crack down, some of the world’s most desperate people suffer.

A populist boomerang

The astounding success of the south Asians who were booted out of Kenya and Uganda in the 1970s and ended up in Britain suggests that Africa would have done well to keep them. Migrants bring dynamism and fresh ideas to poor and middle-income countries as well as rich ones; the lump-of-labour fallacy is just as fallacious in the developing world. Sometimes governments realise this and pull back. In 2014 South Sudan unveiled a mad plan to force companies to sack their foreign workers within a month. It backtracked when firms and charities pointed out that they could not function without Kenyans and other immigrants. South Sudan is not exactly overflowing with skilled graduates who can keep the lights on.

It would be far better for the immigrants and for the countries where they fetch up if governments widened the legal routes for settlement. At present some of the world’s least appealing places have the toughest visa requirements and expect economic migrants to jump through the tiniest hoops. You would think their streets were paved with gold.