What is in the African tulip that can kill insects?

Bioactive chemicals are the internal contents that enable the African tulip tree to kill insects. Flavonoids, phenols and steroids in African tulip tree leaves can be fatal to insect larvae and pupae, especially to mosquitoes whose plasmodium causes malarial fevers. The woody plant in question's (Spathodea campanulata) leaves also contribute to insect kills by the asfixiating, insect-lethal smoke from controlled burns.