Now, I know the lifespan issue was to keep streets from getting crowded.. but I propose a solution for homeowners.
They can buy a powder made up of different foods/chemical powders/etc. That keeps them healthy longer (lengthens lifespan).
Ideas:
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Chicken meal: Made from a plethora of nutrious nutrients, your feathered friend is guaranteed to be flightier and fluffier. Guaranteed to appeal to the most Finicky fowl.
Piggy pellets: Developed to give your porcine friend an iron-clad stomach.
Butterfly Biscuits: Guaranteed to keep your bugs buzzing around your backyard.
Poss ingredients: Jellisac, Barnacle talc, Beans, cherries, lemons, garlic (for immunity), potato, flour, compounds, spinach, etc.