If you have “ants in your pants,” that means you’re fidgeting or “antsy.”
If you’re sitting on the ground at a picnic, you could literally have ants in your pants, which would certainly make you fidget and, very likely, jump up and remove those pants.
The Dictionary of Cliches by James Rogers (1985) says the phrase means “excessively restless or eager.”
And, from Encyclopedia of Word and Phrase Origins by Robert Hendrickson (1997): “Originating in the late 1960s, ‘antsy’ means jittery, restless, nervous. The expression derives from the earlier phrase ‘to have ants in one’s pants,’ which dates back to World War II America and seems to have first been recorded in humorist H. Allen Smith’s book Putty Knife: ‘She dilates her nostrils a lot, the way Valentino used to do it in the silent movies to indicate that he had ants in his pants.’ The quotation shows that ‘to have ants in one’s pants’ can suggest lust, but to my knowledge ‘antsy’ never has this sexual meaning.”
Ants in Your Pants is a Canadian children’s music video television program made and aired by Treehouse TV that aired from November 1, 1997 to 2004.
Chick Webb and his Orchestra recorded a number in 1934 entitled I Can’t Dance (I Got Ants in my Pants).
If you have ants in your pants, perhaps you’ll “make a beeline for” something or someplace, meaning that you’ll go directly there.
This phrase is American and all the early instances of it in print come from the USA. Here is one from The Davenport Daily Leader, January 1808: “Gustav Stengel Sr., of Rock Island, was thrown from his sleigh on Third Avenue in that city yesterday afternoon, the horse becoming frightened and turning abruptly, ripping the cutter. The horse made a bee line for home.”
Because, in that example, the reporter does not explain “make a beeline for” we can assume that the phrase was already common at the time.
The phrase, of course, comes from the behavior of bees, which are very clever foragers. When a bee finds a source of nectar, it returns to the hive and communicates the location to the other bees, using a display called the Waggle Dance. The forager bee performs a short wiggling run — thus the name, with the angle denoting the direction of the nectar-laden flowers and the length of time denoting the distance. The other bees can then fly directly to the source of the nectar, or, “make a beeline” for it.
Ants and bees are noted for being industrious. I hope they have the insect equivalent of a coffee break now and then.