This section is from the book "The Gardener's Monthly And Horticulturist V20", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
I found, two years ago, before the publication of the same fact by a correspondent of the Monthly, that a solution of White Hellebore and soap puts an end to the slug on Rose-bushes. My next experiment with the same solution was on certain house plants infected with scale - cousin-german of the mealy bug. One thorough application seemed to clear the plants of this pest, though a second application was needed two or three weeks after, to dispose of a new, sparse and soft-shelled generation. Any kind of strong soap answers well in solution with White Hellebore. I have a partiality for good soft-soap for such purposes, having found it as effective as whale-oil soap with house plants, and less disagreeable as well as cheaper.
The enquiries of a"Reader," last Autumn, for a cure for mealy bug, recalled my experience with the Hellebore solution in the case of scale; and I suggested to my friend, Mr. Wm. H. Hogg, florist, of this city, to try it upon a large Ste-phanotis, on a trellis in one of his houses, on which the mealy bug had been long established. The following experiment was devised and conducted entirely by Mr. Hogg, who permits me to report it: He made a ball of powdered White Hellebore and whale-oil soap, suited to the cavity of one of Wheeler's screw-globes, attachable to a hydrant or force-pump, for the purpose of distributing insecticide liquids or manures. The action of the water flowing around the ball, inside of the globe, is to dissolve the ball gradually, and distribute the solution of Hellebore and soap through the hose without further trouble. In Mr. Hogg's house the globe and hose were connected with the city water-pipes, and commanded all the pressure needed or desirable. The Stephanotis was washed with the hose at first daily. After a week, or say six applications, the mealy bug had very much diminished, and, with occasional washings, the plant and house have been for several weeks apparently free of the pest, except on closest examination, when some slight traces can still be found.
Practically, the success has been perfect, and the cost in trouble and labor small. Mr. Hogg also bears testimony to the complete effectiveness of this application with the hose to plants infested with scale. I think gardeners will recognize the importance of this experiment. White Hellebore must now be considered as the most powerful insecticide known, which is not also a planticide.