Mosquito Dunk Calculator
Bti dunk count and schedule from water area.
What it does
Mosquitoes hatch in spoonfuls of standing water: ponds, saucers, and tarp folds each breed hundreds weekly. Bti dunks dose the water against larvae for a month each.
The tool above takes standing water area in square feet or meters. It returns dunk count with coverage and replacement timing.
The default 500 ft2 needs 5 dunks for 30 days. The 50 ft2 birdbath zone needs 1, and 250 needs 3.
Mosquito control guidance doses Bti larvicides by surface area with monthly replacement through season. Association resources repeat the per hundred square feet pattern.
Dunks prevent; dumping cures faster: tip saucers weekly and scrub birdbaths. Treat every wet spot together or survivors recolonize the clean ones.
How to use
- Type the water area.
- Read dunk count first.
- Read coverage beside it.
- Read replacement last.
- Treat all standing water.
- Repeat monthly in season.
Formula
- water
- Standing water surface in ft2.
- dunks
- Bti dunk count.
EPA mosquito control guidance frames Bti larvicides with label rate dosing for standing water. Mosquito association resources mirror the dunk per surface pattern with monthly replacement. Metric inputs convert square meters at 10.7639 first.
Worked example
Example: 500 ft2 pond
Imperial defaults: 500 ft2 water.
- Water: 500 ft2 pond surface.
- Rate: 1 Bti dunk per 100 ft2.
- Dunks: ceil(500 / 100) = 5.
- Cover: 30 days per dunk label.
- Replace: every 30 days through season.
- Tool shows 5 dunks, 1 per 100 ft2 for 30 days, Replace every 30 days.
Reference table
| Water | Dunks | Replace |
|---|---|---|
| 50 ft2 | 1 | 30 days |
| 250 ft2 | 3 | 30 days |
| 500 ft2 | 5 | 30 days |
| 46 m2 | 5 | 30 days |
Common mistakes
Try it yourself
Quick checks. Answers sit tucked under each question.
50 ft2?
1 dunk for 30 days.
250 ft2?
3 dunks for 30 days.
0 ft2?
Zero water breeds nothing: enter area above 0.
Questions
Dunk rate?
One dunk per 100 ft2 of standing water, replaced each 30 days. Birdbaths need bits.
Safe how?
Bti bacteria kills larvae, sparing fish, pets, and pollinators when labeled.
Where to treat?
Yes, ponds, ditches, plant saucers, and tarps all breed. Flowing fountains less so.
Kill biters?
No, dunks prevent larvae; adults need source removal and repellents.
Dump first?
Yes, dump saucers weekly and scrub birdbaths. Dunks cover what stays wet.
Stock fish instead?
No, this plans Bti dosing. Fish stocking and aeration need pond pages.