Wow, I always saw these trees as a weed, but did not realise that they were killers of bees!
Below is an extract from Bob (the Beeman) Luttrell's article.
'While I cannot say just what the chemical mechanism of the toxicity is, it seems to be quick, I have watched a bee in its death throes within the flower itself. I have collected many such specimens.'
Here is the link to Bob's article - African Tulip Tree
Botanical Name : Spathodea campanulata
Yet to read it, but wow.
Heard about this tree and its fatal attraction for our bees, probably on the ANBees email list.
Wonder of wonders, my non-gardener next door neighbour actually cut down his African Tulip tree because I asked him to, explaining the bee deaths. This is a guy who's contribution to his garden (apart from scalping his grass) is to cover the soil with black plastic and dump a load of rocks onto it. Even more wondrous is the large Bottlebrush which as I type, is feeding scads of parrots every day.
I have known about this tree for about 4 yrs the devastation it causes the Bees, the lady where my Bees came from told me. Their is another tree which is a problem to Bees and that is the Cadagi Gum Tree, Torelliana. This tree was planted by BCC along the footpaths in late 70's early 80's, They have now classed it as an environmental weed. They were a very popular Tree on the Nurseryman's list.
In another lifetime when I worked in Nurseries and was a volunteer with Men of the Trees, Eucalyptus (as it then was) torrelliana was the 'flavour of the month'. A good shade tree, it was planted everywhere it could be. Much favoured by landscapers, MoTTs repotted so many of them for planting out ... Oh dear, little did we know that even though an Australian native tree, down here in SE Qld, it was an 'exotic' hailing originally from north Queensland and I think the Northern Territory too.
Almost as exotic as Kangaroo Paw (from Western Australia).
Those who were at my place last Sunday would have seen (or nearly tripped over) the stump of an African Tulip tree that I cut down last year due to me getting advice from a native bee expert. The tree was just amazing how difficult it was to kill off the roots. They kept shooting up, up to 5 meres away from the stump itself. Eventually I won the battle, but haven't got around to getting rid of the stump yet. There seems to be less of a consensus about the Cadagi's with some saying that they don't believe there's a big problem with these. Some bees gum up their hives by over using the substance they get from the Cadagi's, while others make better use of the substance.
The Queensland Government website on restrictive invasive plants does mention that it's "Flowers are toxic to native stingless bees" but this doesn't have the same weight and impact as Bob's article.