Oxalic acid Vaporizer.

[Stung]

I want to use a Oxalic acid Vaporizer.  Is the best time at night, because all the bees are there and it is cooler.

[rookie2531]

I wouldn't do it at night just because, you need enough light to work and that gives them enough to attack you. Once on you they will crawl all over until they find a good stinging spot. Best to do it early morning. JMO

[Groundhawg]

I do my OAV treatments early in the morning.  It get almost all my bees, gives them all day to move the vapor around and to start cleaning up and in our area removes the chance of late afternoon or evening thunder storms messing up my schedule of treatment(s).

[Nugget Shooter]

I also treat early morning as here in Arizona it is quite hot after mid morning and too much activity for me