How Termite Baiting Systems Work — Nemesis and Trelona Explained

When termites are detected on a property — in outbuildings, garden timber, or bait stations — but haven't yet established active workings in the main structure, a chemical barrier might not be the first call. In many situations, a baiting and monitoring system is a better fit: a network of stations that intercepts foraging termites, delivers a colony-targeting active, and gives the pest specialist ongoing data about what's happening underground.

This piece explains how baiting systems work, what the two main systems look like in practice, how to tell which approach suits which situation, and why the monitoring cycle is as important as the bait itself.

The principle — baiting kills the colony, not just the foragers

The fundamental difference between a chemical barrier and a baiting system is the mechanism. A chemical barrier creates a treated zone that kills termites as they cross it. A baiting system targets the colony itself.

Here's how: worker termites forage out from the central colony in search of cellulose — timber, paper, dead wood. When foragers find and feed on bait, they carry the active ingredient back to the colony in their bodies. Because termites practice social feeding and grooming — sharing food and contact with nestmates, larvae, and the reproductives including the queen — the active spreads through the colony population over time.

The key word is *time*. Baiting doesn't produce an immediate kill. The actives in both Nemesis and Trelona work by interfering with the insects' moulting process — a biological function that happens across the colony at intervals. The colony doesn't collapse on the day of bait consumption; it collapses over weeks as the active works through the population and prevents successful moulting. That's by design. A fast-kill active would alert the colony before it spread.

This is why baiting is effective where a soil barrier would be difficult to install: rather than treating the soil perimeter, you're targeting the colony's foraging behaviour directly.

What a Nemesis station looks like

Nemesis is a long-established Australian baiting system. Its active ingredient is chlorfluazuron, an insect growth regulator (IGR) that interferes with chitin synthesis — the process termites use to manufacture their exoskeleton during moulting. Without successful moulting, the termite population can't regenerate and the colony declines.

A Nemesis station is an in-ground monitoring container, installed at strategic points around the building's perimeter or in areas of known termite activity. The station contains a timber-based monitoring matrix initially — designed to attract foragers and establish feeding activity. Once feeding activity is confirmed at the station, the monitoring material is replaced with the bait matrix containing the chlorfluazuron active.

The inspection cycle for Nemesis stations is typically every 3 months. At each visit, the pest specialist checks for activity, confirms bait consumption rate, replenishes bait where needed, and logs the findings. This data builds a picture of foraging patterns and colony activity over time.

What a Trelona ATBS station looks like

Trelona ATBS (Above and Below ground Termite System) uses novaluron as its active — also a chitin synthesis inhibitor (CSI), similar in its mechanism to chlorfluazuron. One practical difference from Nemesis: Trelona ATBS comes pre-loaded with active bait. There's no separate monitoring phase; the station delivers bait immediately when foragers locate and start feeding.

Trelona is available in both in-ground and above-ground configurations, which makes it adaptable to a wider range of installation conditions. Above-ground units can be installed directly over known mud tube activity for faster bait delivery; in-ground units provide the perimeter monitoring function.

Trelona ATBS has been shown to be effective against all Australian subterranean termite species, including *Mastotermes darwiniensis* — the large native species found in northern Australia — though in Sydney's metro area, the key targets are *Coptotermes acinaciformis* and *Schedorhinotermes*, for which both systems are effective.

Both work — the choice depends on the site

Nemesis and Trelona are both effective baiting systems in the right conditions. The choice between them isn't about which is better in absolute terms — it's about which suits the specific site, the established activity pattern, and the installation environment.

Some jobs suit the Nemesis monitoring-then-bait sequence: where activity is suspected but not yet confirmed, a monitoring-first installation allows the pest specialist to establish where the foraging is happening before committing to full bait deployment. Other jobs — particularly where active mud tubes are already present and above-ground placement is possible — suit the Trelona above-ground units' faster deployment profile.

The decision should be site-specific and informed by the inspection findings. A pest specialist recommending the same system on every job, regardless of conditions, is working from a preference rather than an assessment. Nick's approach: "Both work. I pick based on the site, not the brochure."

When baiting is the right call

Baiting and monitoring systems are well-suited to several specific situations:

Active property, no structural infestation yet. Where foraging activity is present — in bait stations, outbuildings, garden sleepers, or nearby trees — but hasn't broken into the main structure, a baiting system can collapse the colony before it gets there. This is the ideal use case for baiting as a prevention tool.

Perimeter access is limited. Dense concrete paths, established raised garden beds, courtyard paving, or structural constraints around the building footprint can make continuous soil trenching difficult or impossible. Bait stations don't require perimeter access — they can be positioned wherever foraging activity is present.

Post-barrier monitoring. After an 8-year chemical barrier warranty expires, or during the period leading up to barrier renewal, bait station monitoring provides ongoing detection capability. The stations intercept and identify new foraging activity, informing the decision about what treatment comes next.

Monitoring-first preference. Some homeowners, particularly on newly purchased properties with no previous treatment history, prefer to install a monitoring network and observe before committing to full chemical barrier installation. Bait stations installed at high-risk points — near moisture sources, adjacent to garden timber, at likely entry points — create a detection net.

Why monitoring matters

A bait station you've forgotten about is just plastic in the ground.

This is the point that gets glossed over in most baiting system descriptions: the active ingredient in the station only works if termites find it, feed on it, and carry it back to the colony. That feeding activity has to be discovered and the bait replenished before it's exhausted. The monitoring cycle is the system.

What an unmaintained station looks like: dry, full of debris from rain and leaf fall, bait long-since degraded or consumed without follow-up response. No new bait means no colony-targeting effect. Worse, a pest specialist reviewing the site has no data from the station — no foraging record, no bait consumption rate, no baseline to compare against.

The standard monitoring interval is 3 months. That cadence creates the data record that makes baiting useful: the pest specialist can track whether the colony is declining, whether new foraging has started, and whether the bait placement is correctly aligned with the activity pattern.

Baiting systems can be incorporated into an annual service plan, with the monitoring visits built into the schedule. Annual Termite Service Plans

Next step

If you'd like to understand whether baiting and monitoring suits your property, or if you want to discuss what's already in place, get in touch.

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