The Fifth Day is the newest story on the Hearth & Horizon shelf. It is set in an invented parish cemetery in Oriental Mindoro in the week before All Saints, 2048, and it is text only because the committed audio is over the size cap.
The numbers. A fair sample (every fortieth grave) of 60 graves finds 41 vases with water and 9 with larvae. That is 15 percent of graves, a 95 percent Wilson interval of 8 to 26 percent, or about 190 to 630 of 2,400 graves (point estimate 360). Egg to adult takes roughly 7 to 10 days at 28 C, so a weekly emptying rule has almost no margin when eggs can be laid the day a vase is filled. The story's parish empties and scrubs on day five.
Limits. The five-day margin is the story's choice, not a published rule; the usual advice is weekly. The story does not claim the larvae are dengue vectors. Local health authorities set the real rules.