[The author of this post is a volunteer editor for news site inmediahk.net, which is quoted in this report.]
A protest against mainland Chinese tourists took place in the most crowded shopping district in Tsim Sha Tsui  in Hong Kong on February 17, 2014, with about a hundred protesters yelling at mainland Chinese tourists and calling them “locusts”.
The total number of tourists in Hong Kong in 2012 reached 48 million, with 72 percent coming from mainland China and most of them under the “individual visit scheme “. It has been estimated  that the number of tourists would rise to more than 54 million visits in 2013, with 75 percent coming from mainland China and 67 percent under the “individual visit scheme”, half of which were coming from Shenzhen and Guangzhou.
Though the huge number of tourists has contributed to Hong Kong's economic growth, it has generated a number of social problems. In addition to the seemingly always overcrowded shopping districts, hopping the border to shop for daily necessities has led to the shortage of goods such as infant milk powder  and medicines. Shops that serve local communities’ needs have been turning into luxury good shops for mainland Chinese nouveau riche or pharmacies that sell infant milk powder and medicines for professional cross-border carriers.
However, as the “anti-locust” action targeted individual tourists rather than policymakers, only about a hundred joined the protest and it ended up in a confrontation with pro-government anti anti-locust protesters. The next day, a number of key government officials criticized the act as “barbaric”.
Indeed, many people disagreed with the action. For example, blogger “Montwithin” found  the protesters, who claimed that they were “localists”, unreasonable:
The so-called “localists” in Hong Kong today claimed that they are against the Chinese Communist Party (CCP) […] yet they seldom challenge the Chinese communist institutions and criticize the human rights violations and authoritative nature of the CCP regime. Instead, they like to attack those Hong Kong people who don't share their views when it comes to the “Hong Kong and China conflict”. They cannot agree to disagree. Now, they even harass tourists who can't fight back. They act like the Boxer Rioters  [in Qing Dynasty] by choosing the weak to attack.
Even if society has been overwhelmed by the huge number of tourists, they should direct their anger at the government and demand policy changes.
But Lam Shui-Bun pointed out  that the “barbaric act” is a reaction to the government's refusal to address the problem:
Leung Chun-ying's government had been playing dumb in regard to the problems brought by tourism and the explosion of cross-border social conflicts. [Instead of demanding the government to address the problem], people expressed their anger directly at the tourists. The Hong Kong government should be responsible for such conflict. The incident also reflected the pathetic situation in Hong Kong.
The government wanted to solve the problem by investing in more touristic spots, but the existing shopping districts in Mongkok, Tsim Sha Shui and Causeway Bay are still the “must visit” sites. These districts can no longer take in more tourists. Moreover, the city is overcrowded with tourists and people can feel the uneven distribution of social resources. The capital investing in the tourist sector has killed local shops and pushed up rent and inflation. The economic benefits are in the pockets of big corporations and capitalists, and ordinary Hong Kong people have gained very little. How can they not get angry?
Jonathan Chan, on the other hand, criticized  the protesters for ruining the campaign:
一次絕劣的政治行動，又將本來努力構建的理論正當性被推翻了。[…] 這次「驅蝗遊行」另一個秀逗的地方，是參與者口叫「反殖民」，卻舉著港英旗。[…] 不但會含糊了反對自由行的目標，而且「政治不正確」，給建制派扣「港英餘孽」帽子的籍口。
A extremely poor political action has ruined all the justifiable reasons [for policy changes]. A highly funny scene is that the protesters chanted an “anti-colonialism” slogan during the “anti-locust” rally while holding the British colonial flag […] An action like that has distorted the objective of bringing change to the “individual visit scheme”, and it also has provided an opportunity for the pro-government political forces to label them as “colonial leftover subjects” because of the flag's “political incorrectness”.
Judging from the reaction on popular microblogging site Sina Weibo as translated by Mitch Blatt from China Hush , the British flag did generate public opinion in mainland China that may justify the Beijing government's policy in Hong Kong:
洋羽君在倭国：Haha, raising the British colonial flag to oppose colonialism, this wave of Hong Kong people is really cool. Except for yelling the slogans “Chinaman,” “locusts,” and “independence,” what other tricks do you have? Would singing a big imperial country’s national song make you feel strong? God Save the Queer, Oh, no, I mean Queen.
深情拥浮云：Raising the Union Jack to oppose imperialism. That’s a really good joke.
nbcherry：What do they mean by waving the British era flag? Being a dog for your compatriots isn’t as good as being a British running dog?
渣熊josh：I think British people are laughing until they cry.
XDH-谢: Really funny! If all the people holding up the Union Jack could go to England, then Hong Kong wouldn’t feel so crowded!