New gnats are worse than old gnats

reddie the Fox was jumping over the rocks in a river one day when he lost his footing and fell into a narrow gap. However hard he tried he couldn't wriggle free. Even worse, a swarm of gnats came and began biting and scratching him. Harry the Hedgehog came shuffling by and saw the fox. Being a kind hedgehog he offered to come and eat the gnats that were biting Freddie.

"No, please don't bother," said Freddie gloomily.

"Why ever not?" asked Harry in surprise. "Because these gnats have already bitten me so many times they're getting tired.

If you eat them a new lot will come and start all over again!"