east. These trails and other routes of march are
Use pesticidal dust or pressurized
extremely active from sunset through the early part of
canned aerosols when nests are in wall
voids. Sprays are less effective.
The Western Carpenter ants have principal
With the use of flushing agents,
colonies in trees and stumps from which they forage.
hundreds of ants may remain unaffected
This activity, especially in springtime, brings them
and can relocate the colony in a matter
into the proximity of buildings. They enter structures
of hours or less to trunks, storage
through construction gaps, particularly along electric
boxes, furniture drawers, and other
When indirect treatment is required,
liberal placement of acceptable bait
Control and Management
stations can be used.
Dust, spray or bait can be used on
Search for activity in wall voids, around electric
outside colonies (e.g., in tree rot).
outlets, wall panel grooves, under attic insulation.
Honeydew-producing insects involved in
feeding Carpenter ants should be treated
with pesticides that will not eliminate
Management of the C. modoc may include
parasites and predators (e.g. oils and
removal of stumps
Trees with rotted places should be
elimination of infested firewood near
evaluated by professionals.
caulking of entrances through wall
Carpenter ant infestations often cannot be
control of wood moisture
controlled in one visit. Painstaking inspection is
repair of roof leaks, and the
needed to make management effective. Annual follow-
construction of vapor barriers in the soil
up also assures that necessary habitat alterations have
surface of crawl spaces, attic ventilation
been made by clients.
areas and crawl spaces.
Maintain records of all inspection discoveries and
subsequent recommendations as well as records
mandated by law.
Direct flowable microencapsulated
formulations or emulsifiable
concentrates on foraging paths.
WESTERN CARPENTER ANT
Inject or spray stumps and decayed
spots in trees.
The principal Carpenter ant species in the
If needed for immediate control, spray
northwestern states is the Western Carpenter ant. This
[Use care not to
ant is very similar to the Black Carpenter ant common
contaminate fish, pets, or other outside
in the eastern United States.
animals when spraying. Boric acid dust,
an effective indoor pesticide, can kill
The Western Carpenter ant has a black body with
a slight gray sheen. Its abdomen has a thin covering of
hairs on each segment like the Black Carpenter ant,
Dust wall voids.
but it is less yellow -- more gray. The legs of C.
Apply pesticides around electric outlets.
modoc tend to be reddish.
[Always turn off the main power switch
when injecting dust around the outlet
Behavior and Harborage
boxes; be careful of electrical wires.]
Drill 1/4 inch holes for dust or 1/8 inch
The background of the principal eastern and
holes for pressurized canned liquid
western Carpenter ants are similar, but the C. modoc
produces larger colonies. Clean grass trails an inch
Dust under attic insulation, if necessary.
wide are more prevalent in the northwest than in the
Module One, Chapter 3, Pg 6