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Hydrangea Leaf-tier

Ravageurs et maladies
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Hydrangea Leaf-tier
Photo: Pascale Maynard

Onglets

Description

Summary

The hydrangea leaf-tier (Exartema ferriferanum) is a small moth that lays its eggs on the branches in either the fall or the spring. Upon hatching, the small green black-headed caterpillars sew two terminal leaves together with silk thread, forming an enclosure in which they feed. They feed for about 10 days before pupation occurs. The moths make their appearance a week later. There is only one generation per year. While the damage does not threaten the plant’s life, it may cause the flower buds to abort.

Latin name (genus)

Exartema ferriferanum

Name of host plants

Prevention and control

Physical control

  • In case of severe infestation, cut all stems to 10 cm from the ground in the fall or early spring to eliminate the eggs. This size does not affect the flowering of species that bloom on the year’s new growth. 
  • To control a light infestation, just open the affected buds, exposing the caterpillar to the sun or crush it by lightly pinching the two attached leaves.
  • Discard and destroy all debris from pruning. Never compost debris from infested plants.

Chemical control

  • As a last resort, use a low-impact pesticide whose active ingredient is Bacillus thuringiensis subsp. kurstaki (Btk). The treatment must be applied in early spring, before the caterpillars shelter in the folded leaves.

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