New threat to boxwoods! Look for box tree moth now in WNY

box tree caterpillar
The caterpillar of the box tree moth can damage or kill boxwoods. Look for this invasive species before it becomes established in Western New York. Photo courtesy Matteo Maspero and Andrea Tantardini, Centro MiRT – Fondazione Minoprio [IT]

Don’t let a new invasive insect get established in Western New York.

The box tree moth is an invasive pest that can significantly damage—and potentially kill—boxwood plants if left unchecked.

Boxwood plants imported from Canada this spring could have been infested with the box tree moth.

Box tree moths can produce several generations between June and October, so acting now is essential to prevent this pest from establishing itself in Western New York, according to the U.S. Department of Agriculture (USDA).

What you can do

1. Check any boxwood plants you bought this spring for signs of the box tree moth.

2. If you find any signs of infestation, report it to our local USDA office. Or you can report to the New York State Department of Agriculture and Markets by emailing a picture, the location of where the picture was taken, and the GPS coordinates to the Division of Plant Industry at Plants@agriculture.ny.gov.

3. Please allow agriculture officials to place a box tree moth trap on your property, if needed.

What to look for

Look for young caterpillars hiding among the twigs and leaves. The caterpillars are green and yellow. They have white, yellow, and black stripes and black spots.

The caterpillars eat the leaves and stems, leading to the plant’s death. Signs of feeding include chewed, cut or missing leaves, yellowing or brown leaves, white webbing, and green-black excrement on or around the plant.

The female moths lay their eggs on the underside of the leaves of boxwoods.

Background on the box tree moth

The box tree moth is native to East Asia and has become a serious invasive pest in Europe, where it continues to spread. In Europe, the moth can spread about 3 to 6 miles per year.

The caterpillars feed mostly on boxwood. Heavy infestations can defoliate the plant. Once the leaves are gone, the caterpillars consume the stems and bark, leading to girdling and plant death.

Females lay eggs singly or in clusters of 5 to more than 20 eggs in a gelatinous mass on the underside of boxwood leaves. Most females deposit more than 42 egg masses in their lifetime.

The eggs typically hatch within 4 to 6 days. Pupation occurs on the leaves of the boxwood plant in cocoons. If the boxwood is defoliated, pupation may occur away from the plant using leaves from the surrounding area.

Pupae (cocoons) typically first appear in April or May and are present continuously through the summer and into the fall, depending on the local climate and timing of generations.

Adults first emerge from the overwintering generation between April and July, depending on climate and temperature.

Subsequent generations are active between June and October. Adults typically live for two weeks after emergence.

See more images of the various stages of box wood moth here.

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