in the air for a period of time, then settles to the
Equipment to take care of spill contamination should
always be carried in the service truck.
ground. The droplet size is governed by the nozzle and
valve at the top of the can. After use, a more or less
Why calibrate spraying equipment?
uniform coverage will be attained on exposed
In urban pest management, much is up to the
horizontal surfaces. Very little pesticide lands on
judgment of technicians. A pest control technician
vertical surfaces, penetrates opened cabinets, or clings
should know that the proper dosage of pesticide is
to undersurfaces. Droplets contact pests that have left
being applied; accurate calibration of power sprayers
hiding places, and other insects that fly into the
is important or the amount of pesticide delivered will
insecticide are killed.
be incorrect. Overdosage will contaminate the spray
area or result in runoff. Less than recommended
dosage may fail to control the pest. Technicians need
to regularly look at the output of their equipment.
Flow meters are very helpful to let the technician
know the output of the sprayer over time.
It is estimated that 60 percent of
sprayers have a calibration error up to
A large percentage of sprayers have
greater than 10 percent variation in
discharge from individual nozzles or
Application methods used by different
applicators vary, depending upon
pressure, nozzle tip, etc.
Soil types and types of soil cover
(grass, mulch, gravel) can influence the
rate of pesticides a technician applies.
Manufacturers' instructions, university extension
Canned Pressurized Liquid Sprays
training meetings, label instructions and company
Canned pressurized liquid sprays are not aerosols.
policy should be considered and used to calibrate
Because the coarse, wet spray is not made up of
sprayers. Refer to company policy and core manual
aerosol droplets, little becomes airborne. Compressed
for calibration instructions.
gas mixes with the pesticidal liquid in a pressurized
spray. The gas forces the pesticide through the exit
port, quickly vaporizes, and leaves pesticide on
surfaces. When canned pressurized liquids are part of
Pressurized cans of insecticides
a system that includes crack and crevice nozzles, the
became common in the late 1940s
insecticide can be placed precisely on the target area.
and were first used as aerosol
In a closed crevice, the expanding gas propels the
foggers or "insect bombs." Canned
insecticide in all directions forcing it on all surfaces in
insecticides in u r b a n p e s t
the crevice, rather than shooting it across in a straight
management include canned aerosol
line like a compressed air sprayer. Using canned
foggers (volumetric sprays, total
pressurized liquid sprays requires a firm understanding
release fogs) and pressurized liquid
of the target pests' habits so that pest harborage can be
sprays. (The garden type aerosol or
t h e o v e r - t h e - c o u n t e r aerosol
generally sold to the public for
contact spraying is NOT included in
either of these categories.)
AEROSOL AND FOG GENERATORS
Power aerosol and fog generators break liquid
Canned Aerosol Pesticides
pesticides into aerosol droplets. Reducing the liquid
into droplets is done either mechanically (cold foggers)
Canned aerosol pesticides consist of a pressurized
or by using heat (thermal foggers). Caution should
fluid that produce an aerosol or fog droplet that floats
Mgt & Ctrl, Chapter 2, Pg 3