6.2 Termite Control Techniques & Chemical Barriers

6.2 Termite Control Techniques & Chemical Barriers

[!NOTE] The Paradigm of Structural Termite Defense: Subterranean termite management differs fundamentally from general insect pest control. Because Eastern subterranean termites (Reticulitermes flavipes) nest within the soil and maintain cryptic colonies containing hundreds of thousands of individuals, treating only infested interior framing offers merely temporary suppression. Long-term structural protection requires establishing an impenetrable, continuous chemical barrier between the subterranean colony and the building superstructure, or intercepting foraging populations via slow-acting chitin synthesis inhibitor bait matrices.

[!WARNING] Who may do this work. Every technique in this section — trenching, rodding, sub-slab injection, void injection and in-ground baiting — applies a termiticide, and termiticides are excluded from the Structural class licence. This material is here so that you can recognise a competent termite programme, protect a client from an unqualified one, and answer scope questions correctly; performing it lawfully requires the Termite class licence under s. 35 of O. Reg. 63/09. Treat "can I do this on a Structural licence?" as an automatic no whenever the product is a termiticide.

Eliminating subterranean termite infestations in Ontario structures demands rigorous adherence to chemical dilution standards, specialized sub-surface application engineering, and strict environmental safety protocols. A licensed Termite class exterminator must master liquid soil treatments, concrete drilling geometries, hydraulic delivery dynamics, and in-ground baiting architectures while avoiding catastrophic environmental contamination of potable aquifers or indoor air circulation systems.

---

Continuous Chemical Soil Barriers: Objectives & Chemical Classes

The primary objective of a conventional liquid termiticide treatment is establishing an uninterrupted, continuous chemical treated zone surrounding the exterior foundation perimeter, beneath interior concrete slabs, and within structural masonry voids. This barrier acts as a chemical barrier preventing subterranean termites from accessing structural timbers from their subterranean colonies, while simultaneously isolating termites already trapped inside the framing, causing them to perish from desiccation.

Modern termiticide formulations utilized in Ontario fall into two distinct pharmacological classes:

1. Non-Repellent Termiticides: Formulations containing active ingredients such as imidacloprid (neonicotinoid) or fipronil (phenylpyrazole). Termites cannot detect the chemical in the soil; they tunnel freely through the treated zone, picking up lethal doses via dermal contact and ingestion. Furthermore, because non-repellent chemicals do not cause immediate mortality, exposed workers return to the subterranean nest and transfer the active ingredient to nestmates, soldiers, and the reproductive queen through grooming and trophallaxis (the transfer effect), often triggering widespread colony suppression.
2. Repellent Termiticides: Synthetic pyrethroid formulations such as permethrin or bifenthrin. Termites detect the repellent barrier immediately and avoid tunneling into treated soil. While highly effective when applied flawlessly, repellent termiticides fail if even a minute gap or bridge exists in the chemical barrier; termites will actively seek out untreated fissures as narrow as 0.5 mm to enter the building.

---

Standard Soil Application Methodologies

Applying liquid termiticide requires specialized high-volume, low-pressure pumping systems (typically delivering 15 to 25 psi at the nozzle tip to prevent aerosolization, blowback, and soil atomization). Exterminators employ four primary mechanical delivery techniques:

1. Exterior Trenching & Soil Incorporation

Trenching creates a continuous vertical barrier along the exterior foundation perimeter:

• Trench Dimensions: Exterminators excavate a trench adjacent to exterior foundation walls measuring a minimum of 15 cm (6 inches) in width and 15 cm (6 inches) in depth, or down to the top of the concrete footings if the footings are shallow.
• Application Volume & Rate: The standard regulatory and label rate in Ontario is 5 litres of finished termiticide emulsion per linear metre for every 30 centimetres of depth (or 4 gallons per 10 linear feet per foot of depth) from the soil grade down to the top of the footing.
• Treatment Execution: Half the required chemical volume is applied along the bottom of the excavated trench. The excavated backfill soil is then returned to the trench in layers while simultaneously being sprayed and mixed thoroughly with the remaining chemical emulsion to create a homogenous, chemically saturated soil curtain.

2. Deep Sub-Surface Rodding

When foundation footings sit deeper than 30 to 45 cm beneath the soil surface, digging a full-depth trench down to the footing is practically impossible without undermining structural masonry. Exterminators combine shallow trenching with sub-surface soil rodding:

• Methodology: Long, specialized steel injection rods equipped with multi-directional spray tips (forward and radial dispersal) are inserted vertically into the bottom of the excavated trench.
• Spacing & Penetration: Rod insertions are spaced at 30 cm (12-inch) intervals along the foundation perimeter, penetrating down to the top of the footing.
• Pressure & Volume: Chemical is injected under low pressure (20 to 25 psi) as the rod is slowly inserted and retracted, ensuring overlapping spherical zones of saturation that merge into an unbroken chemical curtain.

3. Sub-Slab Injection (Concrete Floor Drilling)

Termites frequently enter structures through expansion joints, contraction cracks, and plumbing penetrations hidden beneath interior concrete floor slabs (basement floors, attached garage aprons, and slab-on-grade patio extensions). Establishing a horizontal chemical barrier requires sub-slab injection:

• Drilling Geometry: Exterminators drill holes vertically through the concrete slab using heavy rotary hammer drills equipped with 1/2-inch or 9/16-inch carbide bits. Holes must be spaced 30 to 45 cm (12 to 18 inches) apart and positioned no more than 15 cm (6 inches) away from the interior perimeter wall or foundation expansion joint.
• Delivery Rate: Finished termiticide dilution is injected under low hydraulic pressure (15 to 25 psi) directly beneath the slab at the label rate—standardly 5 litres per linear metre (or 4 gallons per 10 linear feet) along the perimeter—to thoroughly saturate the underlying crushed gravel or soil bed.
• Sealing: Following injection, all drilled holes must be immediately sealed flush with structural concrete or non-shrink hydraulic cement plugs to prevent chemical vapor back-drafting into the living space.

4. Foundation Void Injection

Hollow concrete block (cinder block) foundation walls contain internal vertical cavities that provide subterranean termites with direct, sheltered access from soil level up to the wooden sill plate. Exterminators drill each vertical block cell roughly 15 to 30 cm above the exterior soil grade and inject finished termiticide emulsion (typically 7 to 10 litres per linear metre of wall) to cap the internal voids.

---

Environmental & Safety Precautions during Termiticide Treatment

Liquid termiticide treatments involve large chemical volumes (often 400 to 1,500 litres of finished emulsion for a single residential structure). Strict environmental precautions are mandated under the Ontario Pesticides Act and O. Reg. 63/09:

1. Protection of Potable Wells & Cisterns

• Contamination Hazard: Liquid termiticides must never be injected into soil adjacent to or upslope from drinking water wells, cisterns, or natural springs, where gravitational seepage or hydraulic pressure could introduce toxic compounds into potable groundwater.
• Statutory Setback Mandates: Applicators must maintain strict regulatory setback distances (typically a minimum of 15 to 30 metres from any potable well, depending on label directions and soil porosity).
• Alternative Protocols: If an active well or drinking cistern is located inside or immediately adjacent to a foundation, liquid chemical soil injection is strictly prohibited. The exterminator must utilize in-ground termite baiting systems or physical mechanical exclusion barriers.

2. Weeping Tiles, French Drains & Sump Pump Systems

• Modern homes feature perforated plastic or clay drainage pipes (weeping tiles) installed along the perimeter of the footing to channel sub-surface hydrostatic water into an indoor sump pit or storm sewer.
• Discharge Hazard: Injecting termiticide directly into soil surrounding active weeping tiles will cause chemical leaching into the drainage system. The sump pump will subsequently discharge concentrated chemical emulsion into municipal storm sewers, local drainage ditches, or surface waterways, causing severe ecological damage and fish kills.
• Operational Protocol: Exterminators must identify the depth and routing of all weeping tiles before rodding. If treating near perimeter drains, soil must be excavated, treated on an impervious polyethylene tarp, allowed to bind chemically, and backfilled, or alternative baiting methods must be deployed.

3. Sub-Slab Air Ducts & Hydronic Radiant Heating Pipes

• The In-Slab HVAC Hazard: In certain older residential or commercial slab-on-grade buildings, warm-air heating ducts or return plenums are embedded directly inside or underneath the concrete slab. Drilling into or puncturing an in-slab duct will cause liquid termiticide to flood into the air distribution system. Subsequent operation of the HVAC furnace circulates toxic pesticide vapors and aerosols throughout the occupied building, resulting in acute occupant poisoning and condemnation of the structure.
• Radiant Heating Systems: Modern concrete slabs frequently contain embedded hydronic PEX tubing circulating hot glycol or water. Puncturing these pipes causes catastrophic heating failure and property flooding.
• Mandatory Pre-Drilling Verification: Applicators must thoroughly inspect heating systems, review building blueprints, and employ infrared thermography or electromagnetic pipe locators to trace all ductwork and heating lines before drilling.

---

Termite Baiting Systems & Chitin Synthesis Inhibitors (CSIs)

As an environmentally benign alternative to high-volume liquid soil barriers, termite baiting systems exploit the natural foraging biology and social trophallaxis of subterranean termites to achieve complete colony elimination without introducing hundreds of litres of chemical into the soil.

The Two-Phase Baiting Architecture

1. Monitoring Phase: Cylindrical plastic monitoring stations featuring vertical access slits are installed flush with the ground around the building perimeter at regular intervals—typically spaced 3 to 6 metres (10 to 20 feet) apart and within 0.5 to 1.5 metres of the foundation. Inside each station, non-toxic monitoring devices (slotted wood wafers or cellulose matrices) attract foraging worker termites.
2. Toxic Baiting Phase: Technicians inspect stations on a scheduled basis (monthly, quarterly, or bi-annually). Once worker termite feeding activity is confirmed inside a station, the wooden monitor is replaced with a bait cartridge containing a specialized insect growth regulator.

Chitin Synthesis Inhibitors (CSIs) & Colony Collapse

• Active Ingredients: Modern bait matrices are formulated with Chitin Synthesis Inhibitors (CSIs), specifically benzoylphenylurea compounds such as noviflumuron, hexaflumuron, or diflubenzuron impregnated into high-density purified cellulose.
• Mode of Action: CSIs are slow-acting metabolic disruptors. They do not kill termites immediately upon ingestion, nor do they exhibit repellency. Foraging workers feed greedily on the cellulose matrix, ingest the CSI, and return to the subterranean nest, distributing the chemical throughout the entire colony via trophallaxis.
• Molting Failure (Ecdysis): CSIs inhibit the biological enzyme chitin synthase, preventing the production of new chitin. When nymphs and workers attempt to molt (shed their old exoskeleton during growth), they cannot form a viable new cuticle, resulting in fatal ecdysis failure. Within several months, the entire worker force dies. Deprived of food, the soldier caste and reproductive queen starve, resulting in 100% colony elimination confirmed by the complete cessation of foraging.

---

Field Application Scenario: Full Barrier Treatment with Sump & Attached Slab

A licensed structural exterminator is contracted to treat an active Reticulitermes flavipes infestation in an Etobicoke split-level home. The property features a poured concrete basement with an active interior weeping tile sump pit, and an attached 4x6-metre slab-on-grade concrete patio abutting the rear foundation.

The exterminator develops a compliant treatment plan:

1. Exterior Perimeter Trenching: The technician digs a 15x15 cm trench along the 40-metre accessible exterior foundation perimeter. With footings at 90 cm depth, the technician calculates the required liquid volume: 40 linear metres x 3 (each 30 cm increment of depth) x 5 L/m = 600 litres of finished imidacloprid dilution. Half is applied to the trench bottom; the remainder is mixed with backfill soil.
2. Weeping Tile Protection: Knowing the footing features interior perimeter weeping tiles discharging to a basement sump pump, the technician inspects the sump pit during injection. The discharge hose is temporarily diverted into a collection drum to capture any accidental bypass seepage, preventing discharge into the storm sewer.
3. Sub-Slab Patio Injection: To treat beneath the attached concrete patio slab, the technician drills 1/2-inch holes through the slab 35 cm apart and 12 cm out from the house foundation. Using a sub-slab injector at 20 psi, 5 L per linear metre is delivered beneath the slab, and each hole is sealed with an expandable rubber plug capped with hydraulic cement.

---

Critical Exam Traps

[!WARNING] Common Examination Pitfalls for Section 6.2:

• Trap: Trenching Rate Calculation: The label rate is 5 litres per linear metre per 30 centimetres of depth down to the footing. Be prepared to calculate total volume based on wall length and footing depth on the exam.
• Trap: Concrete Slab Hole Spacing: Sub-slab drilling holes must be spaced 30 to 45 cm (12 to 18 inches) apart and within 15 cm (6 inches) of the wall. Holes spaced 1 metre apart leave untreated gaps that termites easily penetrate.
• Trap: Wells & Cistern Prohibitions: You can never inject liquid termiticides into soil immediately adjacent to potable wells or cisterns. Baiting systems are the legally mandated IPM alternative.
• Trap: In-Slab Heating Ducts: Puncturing sub-slab HVAC ducts with a concrete drill allows termiticide to flood into the air handling system, creating an acute indoor toxic hazard.
• Trap: Bait Station Elimination Mechanism: Chitin Synthesis Inhibitors (noviflumuron/hexaflumuron) do not kill termites instantly; they cause mortality during molting (ecdysis) and achieve colony elimination through trophallaxis.