To open a can of worms is to start looking into a matter, or to take some action, that turns out to be far messier and more complicated than it first appeared. Often the trouble is not just that the problem is bigger than expected, but that dealing with it stirs up a whole tangle of further difficulties that would have been better left alone. It is usually said as a warning, either advising against poking into a subject at all, or expressing regret once someone has already started and found more than they bargained for.
What’s the origin of the phrase ‘open a can of worms’?
The image behind the phrase is a literal one. A can of live worms, of the kind an angler carries to a riverbank as bait, is a small tangled mass that becomes considerably more chaotic the moment the lid comes off. That literal use of the phrase predates the figurative one by decades: a 1914 novel has a fisherman tipping his can of worms out on the bank. Etymonline dates the figurative sense, meaning a difficult and tangled problem, to 1951, tracing it directly to that image of the bait can.
The earliest figurative example traced in print is from 1951, in a syndicated article carried in the Ironwood Daily Globe of Michigan, which discussed command arrangements at General Eisenhower’s SHAPE headquarters and said the question was still regarded as a can of worms. The writer used the phrase as though it were already familiar rather than newly coined, which suggests some currency before this citation was written down.
Not every source agrees on the phrase’s print debut. The Oxford English Dictionary is reported to give a later starting point, a 1962 article in the Times, which sits awkwardly against the 1951 newspaper find and leaves the exact first appearance unsettled.
Some have suggested a link between opening a can of worms and the older myth of Pandora’s box, in which curiosity releases troubles that cannot be put back. That connection is plausible given the shared idea of unleashing hidden trouble, but it remains a suggestion rather than an established source. The fisherman’s bait can is the origin actually supported by the evidence.