Catherine Bearder, a Lib Dem MEP for the South East of England, is backing calls to suspend the use of neonicotinoids amid fears of the impact on the bee population.
Members of the House of Commons Environmental Audit Committee have demanded a moratorium on use of the chemicals.
However, the UK Government is still unconvinced and is asking the European Commission to launch a major study to settle the debate.
But Catherine said: “This is beyond complacent. Britain cannot continue to flap around on the issue. We all know how important bees are to our biodiversity.
“A host of experts are concerned about the impact of neonicotinoids and still the Government is dithering and wants more tests.
“Well, get conclusive results and prove them wrong, but until then surely the most sensible step is to err on the side of caution and introduce a temporary ban?”
Catherine has written to Owen Paterson, Secretary of State for Environment, Food and Rural Affairs (DEFRA), to urge the Government not to stall on the issue.
In January, she urged the UK to pay closer attention to what was sprayed in fields and coated on seeds.
Catherine added: “The Government should learn from previous mistakes. Remember dithering on tobacco in the face of evidence it caused cancer and dithering on CO2 emissions in the face of evidence that it caused climate change?
“When will they learn and act on evidence on bees before it is too late? Concerns have been raised about the potential impact of a ban on food production.
“But in the opinion of many of my constituents bees are too important to our crops and therefore our long term food supply, so why take the risk?”
The British Beekeepers Association estimated between 40,000 and 50,000 beehives in South East England.
1) Catherine criticises lack of action and writes to DEFRA in March: http://bearder.eu/en/article/2013/671433/mep-criticises-delay-on-pesticide-ban
2) Catherine calls for European Commission to act in January: http://bearder.eu/en/article/2013/654161/european-commission-stung-on-bee-health