" I. J. L.": " I had a lot of Chrysanthemum plants last summer, in the open ground, covered with Black Aphis. I applied Paris green, but it had no effect whatever. Are they poison-proof or what ?"

[The aphis' do not eat as potato beetles do, but live by suction. They bore the plant structure and suck out the juices, hence poisonous applications are of no use as against them. Aphides, which include the whole tribe of black and green flies, can only be attacked through their breathing organizations. Smoke, oils, and such like must be employed. - Ed. G. M].