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.
Since writing my paper, Mr. W. S. Hogg informs me that, in his experience, (according with my own, ) a solution of whale-oil soap and hellebore, while ridding plants of most insects, including scale, mealy bug and slug, does not dispose of the green fly. Mr. Hogg was, therefore, led to add a very small quantity of Persian insect powder (Pyrethrum roseum), to the above solution. This he finds to be entirely successful, and applies with a hand syringe, out of doors, to keep his rose bushes clear of all insects.