This lovely phrase, as I recall, was often used to describe those focused on notions  unlikely to succeed. Currently, whilst there are very many of us  concerned about ravages to the ecosystems of our planet, some take it further and dye statuary red or glue themselves to something...... to what end I am uncertain. Imagine the planning - getting the dye and mixing it and carting it off to deface something  -  without reckoning how much carbon energy that all takes, especially in cleaning it up. Perhaps it is  satisfying to do and that the despair/ amusement it generates is calming, but whether it makes a jot of difference to their cause, I know not.
There must  have been many throughout history with similar bonnet bees   - why else have the phrase? Perhaps abolitionists started that way and women's votes too, so it can work,.... perhaps.

How very down site behaviour to respond to your own empty thread but I was hoping for some silly bonnet bees to lighten the days. I am not sure when, or if it it is indeed a truth, but I recall hearing of a group in Victorian times who wanted all zoo apes to wear underclothes..... or, one supposes, over clothes to be more exact.
I was going to write primates but doesn't that mean archbishops? And I am sure there has never been any move whatsoever to define what any religious person of what ever faith wears beneath a long frock/robe. (Any such info should go in the Benefits of Religion thread.)

I looked up "Bees in their Bonnets" and I think the earliest reference is from Scotland - something to do with having a bee in your head. I suppose that has to do with sounds going round in your head. (Which reminds me - I wake up most mornings with a song - a different one each day - going round in my head.)
My dictionary calls it 'colloquial' but I don't think of it as colloquial/slang. 
I think primates means a certain type of animal including apes, lemurs and humans. The eccesiastical word may be primature.

Having a bee in one’s bonnet doesn’t necessarily mean that a notion is unlikely to succeed but does indeed suggest having an ever-present obsession. One case (and this isn’t a silly example but rather a tragic one) involves the Hungarian obstetrician Ignaz Semmelweis who in the 1840s made a connection between poor clinical hygiene and the incidence of death among mothers newly delivered of their babies. Childbed fever was rife in maternity wards where postpartum examinations were often conducted by doctors who hadn’t washed their hands between patients. Worse still, in some hospitals physicians were handling the sore and often ruptured parts of mothers after having come strait from conducting post-mortems in the mortuary and again without having washed their hands in the interim.  

Despite having instituted an antiseptic handwashing regime in his own Viennese clinic which saw a drastic reduction in the deathrate among nursing mothers and also having published his findings, Semmelweis met widespread indifference and even opposition from many obstetricians. Frustrated by this, but undeterred, his efforts to get his message across would gradually become all-consuming. He soon earned a reputation for using any medical meeting, social function, dinner party or even casual encounter as an opportunity for him to lecture on the topic. When there was still no general uptake of his idea, he began writing open letters to all obstetricians in forthright and sometimes insulting language. It seemed the more messianic he became, the more his peers shunned both him and his message. This downward spiral sent Semmelweis hurtling towards mental breakdown and he began wandering the streets of Vienna dispensing his wisdom to any passersby, vagrants or even dogs. After having been involuntarily committed to a mental asylum, he was beaten by orderlies and straitjacketed. The beating resulted in his hand receiving a cut which became infected and developed gangrene which in turn caused blood poisoning from which he died a fortnite later aged only 47. It was an extreme irony that so great an advocate of antiseptic handwashing should have been unable to disinfect (or have disinfected) a wound on his own hands by dint of being in a straitjacket. 

In a further tragic twist, soon after his death Semmelweis’ views were vindicated by Louis Pasteur in France (with regard to pathogenic bacteria) and by Joseph Lister in Britain (with regard to antiseptic handwashing). Needless to say that both Pasteur and Lister are giants in the annals of clinical history while Semmelweis is a virtual unknown.