Leaf tier worms on hydrangeas


My hydrangeas are covered with their leaves woven together from I gather the leaf tier worms. Should I cut them off or treat them with something?


The nests of the hydrangea leaf-tier are unlikely to cause long term damage to your hydrangeas, although they are unsightly and may cause particulars flower buds to abort.  There are a number of ways you can deal with the problem.   You can physically control the infestation by cutting  off the infected leaves, by handpicking the caterpillars or crushing them inside their cocoons, or by opening  the infected leaves to expose them to the sun.  If the infestation is very serious you can  cut back the stems of your hydrangeas in early spring or apply  Bacillus thuringiensis, or BT, which is permitted under Ontario’s Pesticide controls, as soon as the larvae hatch.

You will find information about the Hydrandea Leaf-tier  and its treatments on the website of Space for Life (Montreal’s Biodôme, Insectarium, Botanical Garden and Planetarium)  at https://espacepourlavie.ca/en/green-pages/diseases-pests-and-undesirable-plants/hydrangea-leaf-tier