This section is from the book "The Gardener's Monthly And Horticulturist V23", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
The gooseberry and currant caterpillars are great pests to American fruit growers.
The following recipe for dealing with these pests is given by a County Down subscriber to the "Garden," and which he states he had used there thirty years, and never failed with it until 1879, when the daily rain washed the salt off the leaves before it had time to dry or act on the young caterpillars. Mix 1 lb. of common salt with 8 gallons of cold water, but be careful not to exceed that quantity. About the second week in May, or as soon as perforated leaves are observed, choose a dry day and syringe the bushes with this mixture. Repeat the syringing in a week or ten days should more perforated leaves appear. This mixture, though destructive to young caterpillars, will not kill old ones; these must be hand-picked.