Hydrangea leaf-tiers (Exartema ferriferanum), are a small moth whose larvae, (a tiny green caterpillar with a black head), sew terminal leaves together with a silk thread. Once inside this enclosure they feed on the leaves and flower head. These leaf enclosures become wrinkled and puckered and are easy to spot on the plant. They are native to Canada and U.S.A with the majority of sightings coming from the southern tip of Ontario and Quebec and the North/East states of the U.S. ( iNaturalist.ca (n.d.)). Hydrangea leaf-tiers attack various hydrangea species but their preferred hosts are the smooth hydrangeas like Hydrangea aborescens ‘Annabelle’ and Hydrangea aborescens Incrediball^®

Identification and Damage

• Moth: The hydrangea leaf-tier moth is small, with a medium dark brown head and thorax. The forewings are whitish with brown marbling and a dark brown blotch on the lower portion of each wing. The hind wings and abdomen are both whitish in colour. When the wings are closed the white markings are said to look like bird droppings, thus helping to camouflage the moth.
• Caterpillar Larvae: Are slender, light green or yellowish and semi-transparent. They measure about 13 mm (1/2″) long.
• Damage: The leaves at the tips of the branches are sewn together preventing the leaves and flower bud from extending. The cupped leaves become puckered and wavy. In a light infestation only a few stems may be affected but in a heavy infestation 20 or more stems may have these cupped leaves at the end of them. Damage is usually more cosmetic and does not threaten the life of the plant.

Life Cycle

Hydrangea leaf-tiers emerge from the soil in the spring as a small brown and white patterned moths. Like most moths they fly at night and are difficult to spot during the day. They lay their eggs on the branch tips of various hydrangea species. The eggs hatch into small light green caterpillars about 13 mm (1/2″) in length. The newly hatched caterpillars sew two terminal leaves together with silk thread forming a cupped enclosure from which they safely feed. They feed until some time in early summer, then drop to the ground to pupate. In spring the moths emerge from the soil and the cycle begins again. There is one generation per year.

Control

• Physical Control: Prune all stems to 10 cm (4″) from the ground in spring after egg laying has occurred. Pry open the cupped leaves and destroy the caterpillar, or remove the affected leaves and destroy.
• Chemical Control: single application of Bacillus thuringiensis kurstaki (Dipel, Thuricide, others) or a labeled pyrethroid will also be effective (Nixon P. (2012)).

Photo Credits: All photos taken by the author unless other wise indicated.

References

 iNaturalist.ca (n.d.), Hydrangea Leaftier Moth Olethreutes ferriferana, Retieved from: https://inaturalist.ca/taxa/322025-Olethreutes-ferriferana

Nixon P. (2012), University of Illinois, Home and Yard News letter, ‘Hydrangea Leaftier’, Retrieved on Jan. 29, 2021 from: http://hyg.ipm.illinois.edu/article.php?id=359

Other Reading Resources:
Boggs J. (2017), Ohio State University Extension, ‘Hydrangea Leaftier Oddball Damage’, Retrieved from: https://bygl.osu.edu/node/726

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