David McKenzie has an interesting post on the World Bank blog  today about his new paper, which compares the gains to developing world household income from New Zealand's seasonal migration program with forms of microfinance, conditional cash transfer programmes. The results are pretty unequivocal:
As David says, there really is no competition – migrant workers send some of their extra incomes back to their families and enormously increase those families' income. Rather than costly and usually ineffective spending on development, economic growth in poor countries might be more successfully facilitated by programs like New Zealand's. The anti-immigration crowd might not even object if it was seasonally-focused – say, retail during Christmastime and farming work during harvest time – and didn't allow the families of the workers to come with them.