Your warehouse has changed for Christmas. The pest programme needs to follow.

The overflow bay is full. Seasonal ingredients are arriving. Production has extended its hours, and the space beneath the racking is harder to reach than it was in September.

Each change has a sensible operational explanation. Taken together, they can alter where stored product insects are introduced, where they can develop and how readily they will be found. For a technical or warehouse manager, the concern is what happens if activity is discovered when stock is committed, dispatch dates are fixed and access for investigation is at its most difficult.

Cold weather outside offers little reassurance about conditions inside a heated food site. The inspection plan needs to keep pace with the operation.

Winter happens outside

Stored product insects develop according to the conditions around them. In a heated building, those conditions can remain suitable long after outdoor temperatures have fallen.

The Mediterranean flour moth provides a useful example. In one laboratory study, development from egg to adult took approximately 164 days at 15°C and 50 days at 30°C. Cooler conditions slowed development substantially, but did not stop it at 15°C. Those figures describe the study conditions; the species, food and environment on an individual site will determine what happens there (Pakyari and colleagues, 2019 (https://pubmed.ncbi.nlm.nih.gov/30280683/)).

That matters when interpreting winter activity. An insect found in December may have developed from material that has been present for months. The investigation needs to consider older stock and accumulated residues alongside recent deliveries.

Stratton’s field biology work (https://www.strattonem.com/services/field-biology) assesses species, season and site conditions together, examining harbourage, food sources and movement routes. Findings are documented with photographic evidence and a biological rationale, then carried into recommendations and tracked actions. Before the Christmas peak, four connected pressures deserve particular attention.

First, establish where the warmth is

A thermostat gives a reading at one location. It does not establish the temperature throughout a warehouse, around process equipment or within a suspected harbourage.

Where there is reason to suspect warmer conditions near plant, heater outlets or high-level storage, take readings at the relevant locations. Consider those readings alongside susceptible material and previous activity.

The useful finding is specific: a location where temperature, food and time may allow insects to develop. That gives the inspection a priority and the site team something to act on.

Second, check what is staying put

A busy warehouse can move large volumes while particular pallets remain undisturbed. Seasonal overstock, part-used ingredients and material awaiting a decision all deserve attention.

Check where those materials are held, how long they have been there and whether stock rotation is working in practice. An overflow location needs inspection and cleaning coverage as soon as it becomes part of the food storage operation. The site plan should reflect that change, and so should the monitoring review.

Third, arrange access to the places routine cleaning cannot reach

Food residues inside machinery and in difficult-to-clean spaces can support stored product insects. Mixers, hoppers, conveyors and associated equipment need inspection according to the process, the materials handled and the activity history.

Where access requires isolation, engineering support or a production stop, that work needs arranging. John Lloyd’s guidance published by BPCA specifically identifies coordination between pest management, hygiene, electrical and engineering teams as part of effective machinery inspection. “Inspect at shutdown” is only useful once the equipment, access arrangements and responsible people have been agreed. Lloyd, 2018 (https://bpca.org.uk/news/page-2/considering-your-site-specific-pest-risk-assessments/197580).

For sites working to BRCGS Food Safety Issue 9, this also has a direct audit consequence. Clause 4.14.10 requires a documented, in-depth assessment by a pest management expert at a frequency determined by risk, with at least one each year. It must be scheduled so equipment can be inspected wherever stored product insect infestation is a risk. Clause 4.14.9 places responsibility on the site to ensure relevant recommendations from its contractor or in-house expert are acted on promptly. An open recommendation therefore needs an owner and follow-through within the site’s arrangements. BRCGS Food Safety Issue 9, clauses 4.14.9 and 4.14.10 (https://www.nifcc.co.uk/site/wp-content/uploads/2023/11/BRCGS-Food-Safety-Standard-Issue-9.pdf).

An inaccessible area is an inspection gap. It should appear as one in the report, with a clear next step. Otherwise, a recurring access problem can quietly become a permanent omission.

Fourth, follow seasonal ingredients through goods in

Dried fruit, nuts, cereals and other dry ingredients warrant checks appropriate to the material and its history. Look for evidence such as webbing, larvae, live insects and packaging damage, and make sure staff know how to escalate a suspect finding (BPCA guidance on stored product insects (https://bpca.org.uk/pest-aware/page-3/spi-control-how-to-get-rid-of-and-prevent-stored-product-insects-bpca-a-z-of-pests/240955)).

The record needs to connect the finding to the consignment and the decision taken. Once material has moved into storage or production, that connection becomes important to any investigation. For seasonal goods, check that the receiving arrangements cover the ingredients actually arriving and that temporary storage remains visible to the people responsible for pest management.

A moth in a trap is the beginning of an investigation

The catch tells you that an insect reached that monitor. It does not, by itself, identify the material supporting the infestation.

In a three-year study of a commercial food warehouse in the United States, Arthur, Campbell and Toews consistently caught adult Indianmeal moths in an area where no food was stored, but which was connected to the main food storage area. The locations with the highest catches also changed over time. Those findings illustrate why a trap result needs to be interpreted against the wider operation. Arthur, Campbell and Toews, 2013 (https://www.ars.usda.gov/research/publications/publication/?seqNo115=286066).

Identify the species. Review the pattern across locations and dates. Compare it with stock movements, inspection findings and the process. Then decide where further examination is justified.

Low counts need judgement too. Trap position affects detection, so a reassuring total should be read alongside the coverage and condition of the monitoring system. The value lies in explaining what the evidence means and what should happen next. Vick, Mankin and Coffelt, 1980 (https://www.ars.usda.gov/ARSUserFiles/3559/publications/acarins5p5.html).

Stratton carries the finding through to action

A recommendation such as “improve housekeeping” leaves too much for a busy site team to interpret. Useful advice identifies the location, the concern, the work required and its priority.

SEPOS, Stratton’s own operating standard (https://www.strattonem.com/sepos), governs how findings are inspected, recorded, recommended, assigned, verified and reviewed. Actions have a responsible party and an agreed timeframe. Completed work is checked, and the evidence informs the next review of the programme.

Applied before Christmas, that means establishing which findings can be resolved now, which require planned access and which remain open. Hygiene, engineering, technical and operations teams can see where their involvement is needed. It also leaves the technical manager with a record of the decisions made and the work completed as conditions changed.

There is a practical opportunity now to review seasonal storage, investigate unexplained activity and agree access for the shutdown. Once the warehouse is full and production is committed, the same work has to compete with far less room to manoeuvre.

Bring Stratton in before the peak

If your stockholding, production hours or storage arrangements have changed, request a Stratton Operational Site Review. Where the site is a fit, Stratton will review its risk profile, current arrangements and the documentation its audit regime expects, and set out a recommended route in a written summary. Tell us what has changed, where you have concerns and when equipment can next be made accessible.

Request an Operational Site Review (https://www.strattonem.com/contact)