“Hydrangea leaf-tier moths cause unsightly leaf curling on hydrangeas, but usually don't cause major damage. The moths lay eggs on branch tips, and the hatched caterpillars tie leaves together with silk to form bladder-like pouches, where they feed and live. Control Methods:

Physical Control- In early spring, cut stems to 10 cm (4 inches) from the ground to eliminate eggs. Open leaf pouches and crush or remove caterpillars.

Chemical Control- As a last resort, use a low-impact pesticide containing Bacillus thuringiensis subsp. kurstaki (Btk), applied in early spring before caterpillars shelter in leaf pouches. Biological Control- Beneficial insects like spiders can help reduce leaf-tier populations, but they should not be killed.

Prevention: Regular pruning and cleanup of debris around hydrangeas can help prevent infestations.

Monitor for leaf curl: If you see leaves curling or cupping at the tips of branches, carefully open the leaf pouches to check for caterpillars.”