This past week I have noticed several new leaves on my 3 year old Annabelle hydrangea curling up. There are black eggs or insects inside. Is this something serious? Is there anything I can do to get rid of whatever it is? Should I apply a non toxic substance to protect the plant?
Thank you for getting in touch with Toronto Master Gardeners. The insect is the larva of a moth called hydrangea leaf-tier or leaftier (Olethreutes ferriferanum). It affects several types of hydrangeas. Usually they don’t kill hydrangeas but they are unsightly. There are several things you can do to get rid of them. The simplest thing is to clip off the curled leaves as soon as you see them and throw it in the garbage (not the compost). If you have the stomach for it you can pull apart the leaves and squish the caterpillar and rub off the debris and expose the leaves to the sun. Finally if many leaves are affected you can cut back the stems of your hydrangeas in early spring or apply Bacillus thuringiensis, or BT pesticide as soon as the larvae hatch.
For more information please see the following links:
https://www.torontogardens.com/2017/05/whats-wrong-with-my-annabelle-hydrangea.html/
https://www.torontomastergardeners.ca/askagardener/leaf-tier-worms-on-hydrangeas/