Nicotiana - flycatcher?
 

My Nicotiana sylvestris leaves are covered with short sticky hairs which
have trapped a large number of small black flies.

Is this just a defence mechanism?

Are they being killed by the mechanical effect of being stuck on their
backs, or is the nicotine involved at all?

Charles Darwin experimented with putting tobacco leaves in water and in
'meat solution' (beef tea?) and concluded that the leaves were not able
to gain any nutriment from the trapped flies.

Does anyone know any more about this?
--
Kay
"Do not insult the crocodile until you have crossed the river"