Ceratomia undulosa

Ceratomia undulosa, commonly known as the Waved Sphinx, is a moth in the family Sphingidae. Adults are large, nocturnal insects with a wingspan that can reach up to 10 centimeters.

The forewings are characterized by a mottled grey and brown pattern with distinct wavy lines, which provide excellent camouflage against tree bark. The hindwings are generally lighter with darker transverse bands.

The larvae are typical of the sphinx family, featuring a vibrant green body with white diagonal stripes along their flanks. A prominent, curved horn on the posterior end is a hallmark of this species.

Pupation occurs in the soil, where the pupae remain in a protective, dark-brown shell. They are well-adapted to survive through winter in a dormant state underground.

The species usually completes one or two generations per year, depending on the length of the growing season in their native range.

The primary host plant for Ceratomia undulosa is the ash tree (Fraxinus). The larvae are specialized feeders that rely heavily on the leaves of this genus.

Other host plants may include lilac (Syringa) and privet (Ligustrum), especially in garden settings where these plants are common. The damage is strictly caused by the feeding larvae.

Young caterpillars begin by feeding on the edges of the leaf, while older instars can consume the entire leaf lamina, leaving only the midribs behind. This leads to noticeable defoliation.

While mature, healthy trees can usually withstand moderate defoliation, young or stressed trees are at higher risk. Severe infestations can significantly weaken the tree's vigor.

Economic damage is generally low in forest environments, but in ornamental landscapes and nurseries, the presence of these large larvae often requires immediate intervention.

Adult moths emerge in late spring and early summer. They are active fliers and are attracted to light, which makes monitoring their presence relatively simple.

Eggs are deposited individually on the undersides of leaves. The larvae hatch within about a week and begin feeding immediately to support their rapid growth.

The larval stage is most active throughout the summer months. During this period, they consume vast amounts of foliage before preparing for pupation.

By late summer or early fall, the fully grown caterpillars descend to the ground to pupate in the soil. This soil-dwelling stage ensures survival during the winter months.

Effective scouting for the larvae should occur throughout the summer, focusing on the foliage of ash trees during the late afternoon or early evening hours.

Manual removal of larvae is the most recommended approach for home gardeners. Due to their size, the caterpillars are easily spotted and removed by hand.

For larger infestations, biological insecticides containing Bacillus thuringiensis are highly effective and target only the caterpillars without harming beneficial insects.

Encouraging biodiversity in the garden helps maintain natural predator populations, such as birds and parasitic wasps, which keep the moth population in check.

• Maintain tree health through proper watering and fertilization.
• Remove leaf litter from the base of the tree in autumn to disturb pupae.
• Use physical barriers or pruning to manage localized outbreaks.

Chemical control should be the last resort and must be handled carefully to avoid secondary impacts on the surrounding ecosystem and non-target species.