Benzaldehyde was the first repellent I used, and I used it for many 
years. My supply came from FW Jones and Son, Ltd. in Quebec. The former 
co-owner, John Craighead, was on the board that banned its use in 
Canada. After the ban, I bought out their supply over a number of years. 
I thought it worked well. Yes, not so on cold cloudy days, but what does 
work well on cold cloudy days? Not BeeGo. Definately not carbolic acid. 
Charles Mraz pioneered the use of carbolic acid fume boards, and Chas 
and Bill still use it. They don't bother taking off honey on cloudy days.

If you ever used Benzaldehyde, you probably have seen the reason for 
discontinuing its use. As the liquid dries on the pad, stalactites of 
Benzaldehyde crystals form, and if you're not careful, fall down into 
the super. The pads had to be replaced every year.

As far as killing queens...I won't dispute it might happen, but never 
saw it myself. As with any repellent, use the very smallest amount that 
will succeed in driving the bees down. This varies with weather and 
sunshine, and usually requires only a little sprinkle of the repellent 
to work.

Mike

On 4/4/2012 1:41 AM, [log in to unmask] wrote:
> We used Benzaldehyde in the 1960s in the US.  I am not sure why we did  not
> continue using it.
>    

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