Andrew Marani has provided this in depth information on the topic.
The state of Maryland is now doing targeted spraying for Zika. They are using a product by Bayer called Permanone 30-30, which is very toxic to bees, among other things. A link to information about this product is below.
Currently they are not spraying Roland Park, but this can change.
You can get on an email list to be informed where and when “unscheduled” spraying is going to occur by sending an email to firstname.lastname@example.org.
You can also get spraying information on this web page, along with general mosquito information.
And you can follow this twitter feed @MdAgMosquito and receive unschedule spraying information. Probably the simplest solution, for those with Twitter.
My advice to beekeepers in a spray area: Close up your hive before spraying begins at roughly 7:30 PM, most of the girls will be home for the evening by then. It would be best if you closed the entrance with a screen so the bees can still ventilate the hive, otherwise they will likely overheat. If the temperature is not too high (low 80s and below, at a guess) and you can shade your hive, I would also keep them in the next day. Spray water on the hive to cool it and into the entrance so the bees can use the water to do their evaporative cooling trick. If you have a water source set up for your hive, hose it out in the morning to get rid of any spray residue. As an aside, mosquito dunks are a “relatively” benign way of killing mosquito larvae in your water source with minimal harm to the bees. I am available for emailed questions.
A Roland Park bee keeper