Christmas may be the season of goodwill to all men, but a dispute over imported festive trees has led to unseasonally frosty relations between the US and China.
Beetles have been discovered among fairy lights attached to imported Chinese mini-trees and trellises during routine inspections at American ports of entry.
Agriculture officials are worried because the beetles are a close relative of another pest - the Asian longhorned beetle - which the US has spent $200m (£110m) trying to eradicate.
The issue was raised last week at a special committee of the World Trade Organisation, the global dispute forum, that deals with disputes over health rules governing plants and animals.
The US told the sanitary and phytosanitary measures committee that its inspectors had found beetles in 418 consignments of wooden products from China - one in 50 of all those it had checked since late 2002.
The US Department of Agriculture intervened last year to announce a national recall of these products because of fears of a repeat outbreak in New York and Chicago. It has said an import ban will remain in place until Chinese exporters adopt "adequate mitigation measures".
New rules that came into force yesterday dictate that all wood packaging material entering or passing through the US must be either heat-treated or fumigated with methyl bromide.
US trade officials told China the scale of its beetle findings justified further visits by US inspectors to Chinese tree product factories and the completion of a "pest risk assessment".
Chinese officials said the measures already jointly taken by the US and Chinese authorities in response to the interceptions of beetles on wooden Christmas trees were sufficient to allow trade to resume.
Officials were unable to say whether the ban would be lifted in time for exporters to get their goods into the US before the Christmas rush.
Experts believe the issue is unlikely to turn into a major trade dispute between the two blocs, as happened last year over allegations that Chinese exporters were dumping cheap shoes and textiles on the US market.Reuse content