One of the things we've learned is that there isn't anything that Nigel Farage wouldn't blame on foreigners.

This was the stinging riposte by First Minister Nicola Sturgeon during last week's leadership debate when the UKIP MEP railed against immigrants.

The UKIP leader likes to use migrants as a scapegoat for all of society's ills and last week's live debate was another platform from which he pontificated.

Sturgeon and Plaid Cymru leader Leanne Wood were quick to criticise Farage's comments during the two-hour seven-way discussion programme but the leaders of the three main parties were mute.

The issue is an uncomfortable one for Labour's Ed Miliband whose party came under fire last week for selling branded merchandise bearing the slogan 'controls on immigration'.

After the debate he tweeted that Farage's comments were "disgusting", adding: "He should be ashamed."

But shortly before that Labour used social networks to have a go at Cameron's missed immigration targets as if welcoming more people to our shores is a bad thing.

Meanwhile, the coalition party leaders didn't respond to Farage's remarks during the debate.

Liberal Democrat leader Nick Clegg tweeted his condemnation but the Conservatives' David Cameron has yet to comment.

I'm not holding my breath.

The mainstream parties have allowed dog whistle politics to percolate through the discourse and it's difficult to roll back from that.

Not that they're trying.

They simply spout the same rhetoric to suit a narrow political agenda.

I would like to see more politicians offer us the facts on immigration as a starting point.

Then they should go further and be honest about the many benefits of migration.

The reality is most people who come to our country make a positive contribution.

Recent analysis published by Scotland's chief statistician shows half of all migrants aged 16 and above in Scotland are qualified to at least degree level. Many others are working towards qualifications.

The data, based on the 2011 Census, also shows migrants aged between 16 and 74 were equally likely to be in a job as the rest of Scotland's population.

The number of migrants in Scotland stands at 369,000, just 7% of our entire population.

An inconvenient truth for the likes of Farage and other politicians who echo his xenophobic sentiments is that Scotland needs migrants to help address the demographic challenge of an aging population.

Sadly, mainstream party leaders missed the opportunity to talk up immigration during last week's live TV debate.

It was left to Nicola Sturgeon and Leanne Wood to speak up for migrants.

Given the smaller parties have little chance of forming a coalition government after the election on May 7 it looks like the anti-immigration agenda will continue.