Tulip Tree Aphids and Scales Feeding and Dropping Honeydew
Tulip trees (Liriodendron tulipifera) have two primary pests both of which produce honeydew and both of which are actively feeding now. Tulip tree scales are brown bumps that live and feed on branches. They were covered in a recent blog post and detailed article. Adult tulip tree aphids (Illinoia liriodendri) are similar to other aphids. They are yellow with dark antennae and dark cornicles. Winged adults may become darker. Nymphs are smaller and yellow.
Tulip tree aphids occur wherever tulip trees, their only host, grow and particularly on trees planted in landscapes and along streets.
Tulip tree aphids live and feed on the undersides of leaves. Heavy infestations cause leaves to drop, and repeated infestations can reduce tree growth and canopy density. Tulip tree aphids produce copious honeydew, so leaves and surrounding surfaces are often blackened with sooty mold.
Tulip tree aphids overwinter as eggs that hatch in spring. There are several generations during summer and populations can increase rapidly in late spring. Natural enemies typically catch up with them and reduce the populations by early summer. Thus management is often not required. Natural enemies include lady beetles, lacewings, syrphid flies, Orius spp. and many parasitoids. Persistent populations can be managed with horticultural oil or insecticidal soap to reduce their abundance and honeydew production.