Rain Gardens - Ask Extension
What type of mosquito control is safe to use in rain gardens?
Knowledgebase
Rain Gardens #896889
Asked April 10, 2025, 9:37 AM EDT
What type of mosquito control is safe to use in rain gardens?
Charles County Maryland
Expert Response
Rains gardens are designed to slow water down and allow it to soak into soil and stay onsite as opposed to running off and eroding soil. They are normally planted in low areas with plants/shrubs/trees that like wet soil.
That said, they don't usually hold standing water for long.
If you have long-term standing water on your property that stays for many days, (including in old tires or other places that you can't easily drain, you can use a non-toxic larvacide containing Bt, either in the form of granules or donut-like 'dunks'.
Mosquito control mainly consists of regularly dumping out standing water anywhere on your property (and encouraging neighbors to do the same), and using personal protection:
Here is our page with more detail and a great video: https://extension.umd.edu/resource/controlling-mosquitoes/
Christine
That said, they don't usually hold standing water for long.
If you have long-term standing water on your property that stays for many days, (including in old tires or other places that you can't easily drain, you can use a non-toxic larvacide containing Bt, either in the form of granules or donut-like 'dunks'.
Mosquito control mainly consists of regularly dumping out standing water anywhere on your property (and encouraging neighbors to do the same), and using personal protection:
Here is our page with more detail and a great video: https://extension.umd.edu/resource/controlling-mosquitoes/
Christine
Thank you. What about mosquito hawks and crane flies? Is there any recommended treatment rain gardens pertaining to these aforementioned insects?
Justin
Justin
"Mosquito hawks," another name for crane flies, are not a health hazard since they cannot bite, and should not need controlling with pesticides. Like all flies, their larvae need a source of moisture to develop in, and depriving them of that habitat by having soil drain well (and rain gardens designed so they drain as rapidly as possible) should keep their populations naturally low. Plenty of animals, like songbirds and other insects, readily eat crane fly adults. Their larvae eat organic matter (dead plant parts, for example) in damp soil, which, if anything, should help to control mosquitoes indirectly, by depriving them of a food source (organic debris floating in the water).
Miri
Miri
