Leaftier caterpillars taking up residence in your hydrangea?
Hydrangea blooms, a quintessential sight of summer, are on the way. But if you’ve been checking your hydrangea shrub for flower buds, you might have noticed something strange: distorted leaves that seem to be stitched into little pouches.
Inside those pouches are hydrangea leaftier caterpillars (as in “leaf-tier,” one who ties leaves together). “They are unusual little weirdos, and we’ve been seeing them all over this year,” said Sharon Yiesla, plant knowledge specialist at The Morton Arboretum in Lisle.
If you open a pouch, you are likely to find a small, greenish caterpillar about a ½-inch long with a blackish head. “It doesn’t do major harm to the health of the shrub, but it ruins some flowers, and the distorted leaves are unattractive,” Yiesla said.
The insect responsible (Olethreutes ferriferana) becomes a small moth in its adult form. In spring, the moth lays eggs on the branches. An egg hatches into a small caterpillar that weaves together the edges of an unfurling leaf to make a safe hiding place. Inside, the caterpillar will grow while feeding on the surrounding leaves and the developing flower buds. In summer, the caterpillar drops to the ground, where it turns into a pupa, overwinters and develops into next spring’s adult moth.
The leaftier can infest all species of hydrangeas, but in the Chicago area it is most often seen this year on the popular Annabelle cultivar of smooth hydrangea (Hydrangea arborescens ‘Annabelle’) and other smooth hydrangea cultivars, Yiesla said.
“The best thing to do
is just snip the pouches off,” she said. “Crush them and put them in the landscape waste so they will be removed from your yard.” There may be 10 or 15 pouches on a single bush, so go over it carefully.
Cut each affected branch back well below the pouch, at least 6 or 8 inches, making the cut just above a pair of leaves or at the place where the stem joins another branch. “You’ll be removing the flower bud at the tip of the branch, but the caterpillar most likely ruined that already,” Yiesla said. “The other stems on the shrub will still have flowers.”
The Plant Clinic does not recommend insecticides, as they are not likely to be effective against leaftiers. “Removing them by hand is the best way to go,” she said. If the pouches are gone from your garden, the caterpillars won’t be able to complete their life cycle and return next year.