As Knuth's great work on flower pollination, compiled from all available sources, says nothing whatever about the olive, I recently asked Prof. J. E. Coit, of Arizona, to look out for insects upon the flowers. He carefully examined many olive trees in flower at Tucson, and did not find a single insect at the flowers, with the exception of a thrips (apparently Euthrips occidentalis, Pergande), which occurred in great numbers. He kindly sent me some twigs with the Euthrips upon them, and I was able to observe that these insects were profusely dusted with pollen. No bees were seen at all Prof. Coit adds:—“Olive pollen is formed and shed in such enormous quantities that I think the wind among the branches is the chief agent in pollination. If you jar a large branch of olive while it is in full bloom, a perfect cloud of green pollen will be seen to float away on the breeze”.