It's the Fourth of July, and Elmer decides to have a picnic out in nature. When he starts chucking firecrackers, one of them lands near an anthill and pops, making the ants mad. Amused by the ants' complaints, Elmer deliberately begins blasting the anthills to pieces, causing the ants to declare war on him.
The ants organise a military force and train themselves for the retribution campaign. While Elmer takes a nap, the ants steal some of his firecrackers for their own use, then surround his tent and start a siege. Elmer fights back vigorously, but even though he scores a few successes, the ants eventually begin to overwhelm him with their adaptility, greater numbers and thorough military organization, including their navy and air force. Notable scenes include:
- Elmer creeps up on an anthill complex, plunging a lit firecracker down one chute and then stoppering it shut with his finger, causing the blast to blow all the ants present out of their tunnels.
- Elmer notices an ant attempting to stuff a firecracker into the back pocket of his pants. When the ant notices it has been spotted, it quickly extinguishes the fuse, offers the explosive to Elmer, and then sheepishly moves away. When Elmer takes the cracker in his hand to inspect it, it suddenly pops out a larger, spherical bomb, which demolishes his wristwatch.
- Elmer screws together a pipeline to the ant army's headquarters to deliver a firecracker by blowing it through the line. One of the ants nails a rubber band across the other end of the pipe, causing the firecracker to bounce back and end up in Elmer's stomach. As Elmer tries to quench the fuse with a water cooler, the cracker goes off, blasting Elmer into the cooler's tank.
In the end, Elmer beats a hasty retreat, without noticing that his remaining fireworks have been ruptured and are leaking powder. As Elmer disappears in the distance, all a bold ant has to do is light the powder fuse, which goes after Elmer and sets off his fireworks. As the American stars appear in the sky amidst the explosions, the ants give a salute to the spirit of freedom.
- Ant: Of course you know, this means war!
- Elmer: OK, ants! If it’s war you want - it's war you’ll get!