Beginning in the first week of May, our new up-and-coming delphiniums, larkspur and monkshood plants will be subject to infestation by the larva of Polychrysia esmeralda, the leaf-tier moth. They overwinter as eggs or early instar larva and they can infest the plants at the earliest stages of growth. The larva use silk to hold leaves together over the growing buds of the plants. Secure inside this protective cover, they eat away the growing centre of growth. This not only disfigures the plant, but it also removes the flowering bud.
The simplest method to fight this pest is to open up the tied leaves and pick out the larva with your fingers. Dispose of them as you please…I drop them at the entrance of the nearest ants nest.