The hydrangea leaftier is a moth in the Family Tortricidae whose caterpillars use silk applied to the edges of two newly expanding hydrangea leaves to tie them together to create an envelope-like structure within which they feed. These leaf-envelopes tend to occur near the tips of plant stems and can be very obvious. As a result, the two tied leaves may not fully expand when compared to healthy, non-impacted leaves.
Caterpillars are green and partially transparent with a black head capsule and a black thoracic shield which is found on the top of the body segment located directly behind the head. Caterpillars reach approximately 1/2 inch in length. The timing and location of parts of this insects' life cycle may not be entirely understood. Pupation is thought to occur in the ground nearby host plants, so the insect drops to the ground to pupate where it overwinters. Pupation occurs sometime in June. Adults are found in the spring and are small white and brown moths; the white patterns somewhat resemble bird droppings, aiding in camouflage from bird predation. However, this timing and the location of pupation may vary depending upon geographic location. For example, in Ohio, pupal skins have been observed hanging out of the leaf structures by mid-to-early June. This indicates that pupation may occur within the leaf purse, and prior to the winter. Eggs are laid on branch tips of hydrangea. Only one generation is known per year. This insect, although creating visible and interesting damage to hydrangea, is not usually considered to be a serious pest – although occasional localized problematic populations have been reported.
Caterpillars web together emerging hydrangea foliage to create an envelope-like structure that is also sometimes referred to as a "purse". Caterpillars feed on the flower buds within and surrounding leaves. The amount of damage this insect causes to the host plant is relatively minor, however the cupped and tied leaves are an aesthetic issue for some. Smooth hydrangea (Hydrangea arborescens) and its cultivars may be preferentially impacted by this insect when compared with other species of hydrangea.
Monitor for cupped and tied together leaves with silk in the spring. These structures tend to be created on the tips of plant stems. Open the tied together leaves to view the tiny, greenish caterpillars with black heads within, as well as their dark green frass pellets. Tied together leaves may become dark green, fail to fully expand, and resemble a gall.
By gently pulling apart the tied-together leaves, tiny caterpillars are revealed within and able to be mechanically managed by crushing them individually. Removing leaf-envelopes in the early spring or pinching them to kill the caterpillar within can help reduce populations on individual plants.
At this time, not much information is available regarding natural enemies of this insect. Spiders have been noted to move into the leaf structures once caterpillars are finished feeding. The structure houses the spiders, who are beneficial insect relatives (predators) in the landscape. However, it is not thought that the spiders prey upon the caterpillars themselves.
Not necessary for this insect. See mechanical management options above.
Note that the leaf structure created by the caterpillars will protect them from contact insecticides.
Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.
Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.
