TREAT with larvicides
Can’t empty it? Treat it.
Bacillus thuringiensis israelensis — BTi — is a naturally occurring soil bacteria that kills mosquito larvae and nothing else. It’s harmless to people, pets, birds, and fish, and costs about $2 a month.
Mosquito Dunks (donut-shaped) and Mosquito Bits (granules) are widely available at hardware stores. Drop one in and you’re done for 3-4 weeks.
Here’s where to use them:
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Birdbaths
Birdbaths attract birds, and birds eat mosquitoes! But a stagnant birdbath breeds far more mosquitoes than any bird will eat. Drop a BTi dunk in. It won't harm the birds, just the larvae.
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Ornamental ponds and water features
If it’s decorative and holds still water, it needs a dunk. Fountains with pumps are lower risk since moving water discourages egg-laying, but if the pump is ever off for more than a few days, treat it.
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Planter Saucers
If you’re not routinely tossing standing water in the saucers beneath your container plants, sprinkle some mosquito bits in there every 2 weeks!
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Drain spouts
Sprinkle mosquito bits into any downspouts, corrugated drain pipes and/or gutters that hold standing water in between rain storms.
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Rain barrels
Keep lids tight and cover any openings with fine mesh. Drop a BTi dunk in monthly — it kills larvae and is completely safe for your plants, pets, and any wildlife drinking from it. A treated, screened barrel is a genuinely mosquito-safe setup.
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Catch basins
Those metal grates in the street and sidewalk collect standing water and are prime breeding grounds.
DC residents can request treatment through DC Health, but you can also treat them yourself with BTi dunks. If you see one near your home that’s consistently wet, adopt it.
We’re building a map of untreated catch basins across the Hill. Get involved → if you want to help!