Across India, increased access to ultrasound technology, which allows parents to abort unwanted baby girls, has helped create this imbalance. It tends to be most marked in prosperous areas, where expectant parents can pay for the tests and the abortion that may follow.

Indeed, far from being an ancient legacy of poor, backward societies, the practice of female foeticide is flourishing as India's economy booms. In the capital, New Delhi, the gender ratio is more unbalanced than the national average, with 821 females to every 1,000 males. Some of the greatest imbalances occur in the prosperous neighbourhoods of the city.

And recent research suggests female foeticide is on the rise. Actionaid and Canada's International Development Research Centre found that in four of the five states surveyed in 2008 - Punjab, Haryana, Madhya Pradesh and Himachal Pradesh - the proportion of girls to boys had fallen further since the 2001 census. In one area of Punjab, among high castes, the ratio of girls to boys was 300 to 1,000.

Nandgaon, where most men work as farmers, offers a microcosm of growing bachelor angst in such places.

The Indian Red Cross Society, which campaigns against female foeticide across the country, estimates that in this village, which has a population of 1,700, at least 100 men have passed the age range considered ideal for marriage - 20 to 25 - and at least five brides have been imported from other states. At least 100 women from outside Haryana have been bought by men in the wider district of Bhiwani, one of Haryana's 21 regions. All have been bought, whisper villagers, who also speculate that the Muslim brides are illegal immigrants from Bangladesh. No husband will say how much he paid for his bride.

Dilbarg, a 30-year-old farmer who goes by one name, says he did not, like so many of the old men he knows, want to grow old without a wife. This February, he married 22-year-old Sharmila, who comes from Tripura, a tiny state in India's remote northeast, and is too shy to speak in public.

Older farmers, still wifeless, say they regret not having looked outside Haryana for wives when they were Dilbarg's age.

'The richest men here got the girls first,' says Suresh Kumar Yadav, a 42-year-old farmer who has travelled to India's holiest sites to pray for a wife, in vain. 'Men with government jobs too - you don't want to give your daughter to a poor farmer these days.' It is, however, farming that has contributed to the gender imbalance in places like Haryana and Punjab.

In agricultural societies, boys inherit the land, which raises a son's worth far above a daughter's.

The reasons parents opt for sons over daughters can be different in urban areas. Here, a trend towards smaller families plays its part: many couples who choose to have only one child choose to make that child a boy.

'My sister had one child, a son, and that's an increasingly common middle-class thing,' says Indrani Bhattacharya, an office manager in Delhi. 'My sister-in-law also had one child, a daughter, and I know for a fact she was disappointed. Boys seem less hassle - they live with their parents, while girls move out when they marry; and with boys, parents don't have to worry about sexual harassment, which is a big problem in the cities.'

Whether it is in a rural farmhouse or a high-rise city apartment, underlying India's preference for sons is a belief that girls are liabilities, who require protection and fat dowries. The practice of paying a husband and his family for marrying a girl was banned in 1961, but dowry violence - when a woman is abused in her in-laws' home for paying an insufficient price - is on the rise, suggesting dowries are also increasing, according to NGOs.

Even in families that do not pay dowries, and where girls may be well-educated and lucratively employed, females tend to be viewed as burdensome because they are perceived to require more care and protection than men, says Dr Puneet Bedi, an obstetrician and campaigner against female foeticide based in Delhi. 'Everyone wants boys - not just the rich,' he says. 'But it is the rich who can easily afford to access the technology.'

Female foeticide is a problem across Asia. On March 8 - International Women's Day - the UN said that between them, India and China were 'missing' some 85 million women who had died from discriminatory health care or neglect - or who were never born at all.

A day later, India's government succeeded in passing a controversial bill that reserves a third of the seats in parliament for women. This signalled its intention to improve the lot of Indian women, who lag far behind men on most social and health indicators.

It was hailed by activists for women's rights. But campaigners say that on issues like female foeticide, change is a long way off.

India banned gender selection and selective abortion in 1994. But most of the country's 35 states have yet to report a single violation of the law, says Unicef, which estimates that sex determination has become a business worth some US$244 million in India. Telling parents their baby's sex is a crime that is carried out 'by every doctor with almost no exception', says Bedi.

Instead of making sure the law is implemented, the government in New Delhi has focused on educating people about female foeticide. In recent years, Indian cities, towns and small villages have been bombarded with 'save the girlchild' campaigns by government and NGOs.

In the fields around Nandgaon, no one will confess to preferring sons. 'The girlchild is precious and equal,' says Ramdevi, a farm labourer carrying a bundle of fresh grass on her head, in language reminiscent of government awareness campaigns.

Ramdevi happens to have three sons, she adds, 'but everyone wants daughters as much'.

With the failure of the law, and awareness campaigns, activists against female foeticide hope that the social effects of the skewed sex ratio - becoming so dramatic in places like Nandgaon - will change attitudes and make parents think twice before they opt to abort a daughter.

Villagers here say that the dearth of females has already changed social mores. No girl is allowed to marry into another village unless her in-laws promise to give Nandgaon a girl in return.

More hopefully, the dearth of brides seems to have had an effect on dowry customs: dowries are getting smaller or disappearing altogether, say villagers; instead, the onus is increasingly on young men to provide well for their future brides.

Meanwhile, the lonely bachelors' new quick fix, buying brides from impoverished parts of India, seems likely to do little to enhance the status of women.

Babulal Yadav, a 50-year-old farmer and a bachelor, has certainly revised his notions of women since he was a young man with hopes of a local bride.

'I don't mind what caste she is, what religion, or what she looks like anymore,' he says.

'I just want a nice girl to look after me and give me a son.'