Management of Drywood Termites: Past Practices, Present Situation and Future Prospects - Urban Insect Pests: Sustainable Management Strategies - page 141

neoteny and propagation/transport on small
resources. The lack of verifi able detection
techniques/technology is the major chal-
lenge for identifying and delimiting infest-
ations as well as determining the effi cacy of
an intervention. Visual search remains the
mainstay of the inspection process because
of the cost and limitations of detection
technologies (Table 9.1) (Scheffrahn et al .,
1993; Lewis, 2003). The diffi culty in locat-
ing and delimiting the extent of infestation
is complicated by the small size of knock-
out holes (Fig. 9.2) and construction prac-
tices that leave most structural wood hidden
from view (Smith, 1995; Lewis et al ., 1997;
Potter, 2011). Construction with non-
cellulosic material or pressure-treated wood
is a viable, yet expensive, alternative that is
complicated by the fact that furniture and
wooden materials brought into a structure
could be a source of infestation. The biology
of many drywood termite species ensures
that once in a structure their swarming
activity represents a threat of new infest-
ation. Exclusion using paint, screens or
other materials has not been thoroughly
investigated (Lewis, 2003).
Drill-and-treat (via subsurface injection
of liquid or dust) for local remedial inter-

ventions is hampered by the architecture of
the drywood gallery system - assuming a
gallery is located during treatment. That
architecture effectively and consistently
prevents complete coverage of the entire
gallery system when using foam, liquid or
dust formulations, owing to back pressure
(because of dead-end galleries) and the
narrow interconnecting galleries that can be
blocked by pellets or termites (Fig. 9.3)
(Grace et al ., 2009; Hickman and Forschler,
2012). Drill-and-treat interventions must
therefore involve a slow-acting, non-
repellent active ingredient and time
(months) must be allowed for elimination of
an infestation. Residual activity of the
active ingredient is important to prevent re-
infestation because alates will utilize
abandoned galleries as a starting point for
new colony formation. It is also possible
that colonies present during treatment but
not connected to the treated galleries could
contact the residual pesticide when their
gallery system expands into the vacated -
and treated - galleries.
Properly conducted fumigation is effect-
ive but expensive and leaves no residual
protection prompting repeated applications
over the lifespan of a structure (Potter,

(a) (b)

Fig. 9.2. A photograph of structural lumber with drywood termite knock-out holes (indicated by arrows) that
are (a) plugged and (b) not plugged. These images illustrate one of the diffi culties involved in visually
inspecting for signs of infestation. The diameter of a knock-out hole is approximately 2-4 mm.