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plants. The bad news is that they BTM is most easily
concentrate on boxwood plants recognized by the
and can kill the shrub. Boxwoods webbing the caterpillars
are extremely popular in the nursery create as they mature,
industry and have been used in which is visible by spreading
areas with heavy deer populations the branches and looking into the
since they do not like to feed on the interior of the shrub. Caterpillars
aromatic foliage. can be detected by heavy,
characteristic feeding patterns, with
If you are in a situation with BTM
leaves appearing “peeled” or with
and need to remove clippings or
leaves that have only the midrib
entire shrubs from an infested site,
remaining. Green-black balls of frass
please take precautions so the insect
(droppings) are also indicative of an The ‘melanated’ brown variant
does not spread to new locations. of adult Box Tree Moth.
infestation.
At this point, the recommendation
is to bag the infested plant material, The BTM caterpillar is black and
safeguard it on site and contact MDA green, with green, yellow, black and growing season are going to make
in Annapolis. white longitudinal stripes. Adult monitoring for this pest a summer
moths are typically white with a long event.
There is a large industry that involves
cutting boxwood stems in the fall brown margin around their wings. Treatment materials:
months. These cut stems are used A less common variant of the BTM Cornell University Extension has
in holiday decorations. Since larva moth is fully brown with small white published a list of registered
overwinter on rolled up leaves, BTM spots on the forewing. They have a insecticides for control of the box tree
can easily move from an infested wingspan of approximately 1.5 inches. moth. Since caterpillars can be found
area to previously non-infested areas. BTM eggs are deposited on the deep in very full shrub you will need a
Local cut flower growers and florists underside of boxwood leaves and sprayer capable of penetrating into
need to be aware of this pest and its take about 3 days to hatch. Newly the inter canopy. A
potential to spread to cut boxwood hatched caterpillars feed on the https://cornell.box.com/v/BTM-
stems used in holiday decorations. underside of the leaf, then continue Insecticides-Commercial
to defoliate the plant as they grow
larger, and eventually strip the bark Pictures courtesy of https://cals.
under heavy feeding conditions. cornell.edu/new-york-state-
Depending on the weather, integrated-pest-management/
caterpillars mature into adult moths outreach-education/fact-sheets/
in about 14 days. The BTM can have box-tree-moth
several overlapping generations
between May
and October.
They overwinter Stanton Gill, Extension Specialist
as caterpillars in Nursery and Greenhouse
and can survive Entomology and IPM, Central
at temps as low Maryland Research and Education
Center, University of Maryland
as -22F (-30C). Extension and Professor with
The multiple the Sustainable Agriculture
overlapping and Environmental Horticulture
generations Program, Montgomery College
during the

Eggs are deposited on the underside of boxwood leaves

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