Dogwood
Borer
Pest: Dogwood Borer (Synanthedon scitula (Harris))
Order: Lepidoptera
Family: Sesiidae
Host Plants:
Primarily a pest of flowering dogwood (Cornus florida
) but also may attack flowering cherry, apple, and various other
deciduous hosts.
Description:
Flowering dogwoods that are older and especially those that
have been wounded by mowers or line trimmers are most susceptible.
Entrance holes with exuded sawdust are to be found on the main trunk
and larger branches. Larvae feed in the inner bark area and damage
the vascular system. Classic symptoms of infestation are: top die-back
of the plant, adventitious growth along the trunk, main branches
and from the base of the trunk. Also, sloughing of the bark may
be another symptom. Repeated infestations can greatly diminish the
health and aesthetic appearance of the host.
Life Cycle:
The clear-winged moth adults, of this pest, appear around the
time when the last of the petals have fallen from flowering dogwood
(late spring-early summer). Their flight activity continues into
September. Eggs will be laid on the bark, usually near a wound or
branch collar. The newly hatched wood-boring caterpillars require
an opening to successfully enter through the bark into the cambial
area. Larvae will feed for one year and pupate the following spring.
Management Strategies:
Adults appear beginning around 250 growing degree days mid-late
May in Massachusetts) and continue into September. Specific pheromone
traps are available and can help to pinpoint the exact time of adult
flight and egg-laying activity. However, this offers extremely little
in the way of management. The best strategy is to prevent wounding
of the host plant. This involves placing bark mulch around the base
of the tree to suppress weed growth thus eliminating the need to
bring mowers and line trimmers within close proximity of the trunk.
Infested trees are best managed with the use of entomopathogenic
nematodes. They can be applied as a liquid spray directly to the
trunk and main branches of the host. In low to moderate infestations
this should be done in August or September. In more severe infestations,
an application should be administered in late April and again in
August or early September. Preventative sprays during the adult
flight period are available with certain residual-action chemical
pesticides but repeated applications are necessary and, given their
persistence in the environment, are not recommended as a standard
practice. Entomopathogenic nematodes have proven to be at least
as effective as chemicals and therefore, their use is highly recommended.
Images:
Old entrance / exit holes of the dogwood borer on a flowering
dogwood. (R. Childs). |
Wood
attackers index:
Asian
Longhorned Beetle
Asian
Longhorned Beetle in Massachusetts
Bronze Birch Beetle
Dogwood Borer
Emerald Ash Borer  - Courtesy
of USDA Forest Service
Rhododendron Borer
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