SF fruit flies breed year-round due to mild climate and ubiquitous compost bins, and standard traps fail because local populations have adapted to apple cider vinegar lures

San Francisco's mild, fog-buffered climate never gets cold enough to kill off Drosophila melanogaster populations in winter, so fruit fly generations overlap continuously rather than resetting each spring. So what? This means infestations compound — each female lays ~500 eggs, and with no winter die-off, populations in a single kitchen can reach thousands within weeks. So what? San Francisco's mandatory composting ordinance (SF Environment Code Chapter 19) requires every residence and business to maintain a compost bin, which provides a perpetual breeding substrate of rotting organic matter on virtually every block. So what? Standard consumer traps — apple cider vinegar funnels, sticky traps, commercial bait stations — show diminishing returns because Bay Area fruit fly populations have been under constant selective pressure from these exact lures for over a decade since composting became mandatory in 2009, favoring flies less attracted to acetic acid. So what? Residents resort to expensive, repeated professional treatments ($150-300 per visit) that only suppress adults without addressing the larval reservoir in municipal compost infrastructure they legally cannot remove. So what? The problem persists structurally because the city's environmental policy (mandatory composting) directly conflicts with pest control, and no agency owns the intersection — SF Environment manages composting, DPH manages pest complaints, and neither has budget or mandate to engineer compost bin designs that exclude Drosophila oviposition. Building managers have no enforceable standard for compost bin sealing, and the current green bin design has 3-5mm ventilation gaps that are perfectly sized for fruit fly entry.