Geraldine, I’m gratified that you found these suggestions helpful. I’ll add a few more thoughts in response to your reply.
Being that this kind of cockroach thrives in the sanitary waste environment, I’d focus on that as the most likely source. Were the roaches present prior to the refurbishing of the toilet? If so, there might be a rotted pipe in the floor or wall. In that case, you might contract with a plumbing vendor who can inspect using a fiberoptic video camera or by performing a smoke test of that plumbing line. In many cases, there’s a gap around the waste pipe beneath or behind the commode. This will allow roaches that wander out of the pipe to enter ‘our’ world. Sometimes, the wax ring connecting the commode to the waste pipe degrades, or the newer silicone rings (if present) don’t seal effectively. I think these are worth investigating. I believe that the pigeons and swifts would likely be ‘red herrings’; that is, irrelevant to the cockroaches. The birds can, however, cause yet other headaches. They often come complete with their own friends and ectoparasites, such as bird bugs (related to bed bugs), biting mites, and scavengers that will feed on carcasses, droppings, and nesting materials. The scavengers (such as dermestid beetles and keratin-feeding moths) might then pose some risk of destroying organically-based accessions in the museum. It is great that you have a good housekeeping routine, and that foods are prohibited. Too many museums are putting cafes in close proximity to their most valuable holdings, then the personnel wonder why they’re plagued by mice, roaches, and flies. The diatomaceous earth is inert and should (if applied appropriately) not pose any measurable risk to people, the building, or the collections. American cockroaches are covered by a secreted waxy layer. The diatomaceous earth particles will stick to that wax. American cockroaches are exceptionally finicky about their personal hygiene. They constantly groom themselves, to the point of putting cats to shame. While at rest they regularly sweep their legs over their wings and bodies and then ingest whatever has been rubbed off. The diatomaceous earth particles will abrade that waxy coat and hasten water loss through their integument. If the rate of desiccation exceeds their ability to rehydrate, they’ll soon (hopefully) resemble a potato crisp. Accordingly, it is critical to find and eliminate sources of water (e.g. water leaks, condensate). Pursuing any of these steps (including the roach gel) will put some pressure on the roaches present. Combining several (or all) these strategies will conspire to further accelerate the process. If you don’t find and seal the source(s), however, the problem will persist, much like that annoying relative who came for a visit and just won’t leave. All the best! Rich From: [email protected] <[email protected]> on behalf of Geraldine Finlayson <[email protected]> Date: Friday, June 19, 2026 at 10:52 AM To: [email protected] <[email protected]> Subject: RE: [PestList] Recommended pest treatment for American cockroach (Periplaneta americana) Dear Rich, Thank you so much for these thoughtful suggestions. The only drains in the immediate vicinity are those associated with a recently refurbished toilet, and as far as one can ever be certain in an old building, we are confident that this is not the route of entry. The building itself is historic, with wooden floors and voids that inevitably create potential harbourage points, but the moment the problem seems to be in this area (we do get the odd one elsewhere in the building, but these are probably getting in from the street). We have also had recent issues with pigeons on the roof, which we are addressing separately. That work is complicated by the presence of nesting swifts in the attic, so we must proceed with great care to avoid disturbing them. I mention this only because it illustrates the layered constraints we are working within when considering any intervention, but the pigeon droppings are certainly an issue. Having said all this, on the housekeeping side, we have a good cleaning routine, and food is not permitted in any of these areas. With children this is always a challenge, but they are generally very good, and our staff are diligent about removing any organics promptly. Your confirmation that targeted gel baits remain appropriate is very helpful, as this aligns with our own thinking, and it was the contractor’s reluctance that was worrying us (had we missed something). Thanks for the suggestion about the small folded glue traps in non‑public, inaccessible areas, we will certainly try that, and We’ll explore further the possibility of diatomaceous earth and whether it could be used safely in cracks and crevices without creating dust exposure risks. Thanks again for your help. Your guidance is much appreciated. Kind regards, Geraldine Prof G Finlayson, GA, GMD, MSc, PhD, FSA, RFUG [Gibraltar National Museum logo 2018] CEO, Gibraltar National Museum & World Heritage Site Coordinator 18-20 Bomb House Lane • P.O. Box 939 • Gibraltar GX11 1AA e [email protected]<mailto:[email protected]> w gibmuseum.gi<http://www.gibmuseum.gi/> t (+350) 200 74289 - - - - - - Adjunct Professor Liverpool John Moores University - I said to the almond tree, "Sister, speak to me of God." And the almond tree blossomed. - Nikos Kazantzakis ****************************************************** This message, together with any attachment, is intended only for the use of the individual or entity to which it is addressed, and may contain information that is legally privileged and confidential. If you are not the intended recipient, or a person responsible for delivering it to the intended recipient, please be informed that any dissemination, distribution, copying, printing or retaining of this message, or any attachment, is strictly prohibited. If you have received this message in error, please advise the sender by reply email, and delete the message. From: 'Pollack, Richard J' via MuseumPests [mailto:[email protected]] Sent: 19 June 2026 12:06 To: [email protected] Subject: Re: [PestList] Recommended pest treatment for American cockroach (Periplaneta americana) Geraldine, Interesting conundrum. I’d focus initially on discovering and blocking the likely source(s) of the American cockroaches. What waste plumbing lines serve this area? Is there a dry drain? A gap around the toilet? A breached pipe? Are food wastes or compost present in or adjacent to the facility? In concert with source reduction, I’d suggest efforts to suppress the abundance of the free ranging roaches. I, too, favor the gel baits, applied in strategic areas and in manners to reduce contact with wandering fingers of visitors. I’m aware of the concerns and restrictions on the use of glue boards for mice. Can small, folded glue traps not be used for the roaches? Might you consider the use of diatomaceous earth in cracks and crevices where roaches might dwell? Lastly, consider redoubling efforts to ensure that any food or sweets are secured, and enhance the frequency or extent of cleaning to remove any organics that roaches might find attractive and nutritious. Best wishes for success. -Rich Richard J. Pollack, PhD Senior Environmental Public Health Officer Environmental Health and Safety (EH&S) | Harvard Campus Services 46 Blackstone Street., Cambridge, MA 02139 C: 617-447-0763 www.ehs.harvard.edu<http://www.ehs.harvard.edu> [A blue and black logo Description automatically generated]<https://www.linkedin.com/in/richard-pollack-6818997/> From: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> on behalf of Geraldine Finlayson <[email protected]<mailto:[email protected]>> Date: Friday, June 19, 2026 at 4:23 AM To: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> Subject: [PestList] Recommended pest treatment for American cockroach (Periplaneta americana) Dear colleagues, I would appreciate your advice on a point of practice that has arisen with our contracted pest‑control provider. We have an active issue with American cockroaches in a small number of rooms, and we requested the application of gel bait in the affected areas only. The contractor has replied that they “cannot indiscriminately apply gel everywhere,” which does not reflect what we asked for. From my perspective, targeted gel placement in affected rooms — in cracks, crevices, and appropriate bait‑point locations — is standard IPM practice. I am aware that gels should not be placed on exposed public surfaces, in areas accessible to children, or in ways that contradict COSHH/HSE guidance, but none of these apply to the specific rooms in question. At the same time, they have recommended the use of a Coopex Maxi smoke generator insecticide (permethrin 13.5% w/w with potassium chlorate) in these rooms that are used by school groups, and which contain museum exhibits in cases, and in storage cupboards. This seems entirely inappropriate as the exhibits would be exposed to chemical residues and particulates. I am struggling to reconcile their reluctance to use targeted gel in affected rooms with their willingness to propose a smoke generator in a mixed‑use public and collections space. Before I go back to them, I would be grateful for your views on: * Whether there are legitimate technical or regulatory reasons why a contractor might decline targeted gel placement in affected rooms * Whether you would consider a permethrin smoke generator acceptable in a room used by the public and contains museum collections * How you would normally expect a contractor to manage a cockroach issue under IPM principles in a museum environment Any guidance or examples from your own institutions would be very helpful. I want to ensure that our expectations are aligned with best practice and that we are not being given an inconsistent or overly restrictive interpretation of the regulations. Kind regards Geraldine Prof G Finlayson, GA, GMD, MSc, PhD, FSA, RFUG [Gibraltar National Museum logo 2018] CEO, Gibraltar National Museum & World Heritage Site Coordinator 18-20 Bomb House Lane • P.O. Box 939 • Gibraltar GX11 1AA e [email protected]<mailto:[email protected]> w gibmuseum.gi<http://www.gibmuseum.gi/> t (+350) 200 74289 - - - - - - Adjunct Professor Liverpool John Moores University - I said to the almond tree, "Sister, speak to me of God." And the almond tree blossomed. - Nikos Kazantzakis ****************************************************** This message, together with any attachment, is intended only for the use of the individual or entity to which it is addressed, and may contain information that is legally privileged and confidential. If you are not the intended recipient, or a person responsible for delivering it to the intended recipient, please be informed that any dissemination, distribution, copying, printing or retaining of this message, or any attachment, is strictly prohibited. If you have received this message in error, please advise the sender by reply email, and delete the message. From: 'Armando Mendez' via MuseumPests [mailto:[email protected]] Sent: 10 June 2026 14:29 To: [email protected]<mailto:[email protected]> Subject: RE: [PestList] Suggestion regarding pest treatment in an art gallery stationed in Mumbai, India [like] Armando Mendez reacted to your message: ________________________________ From: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> on behalf of David Loughlin <[email protected]<mailto:[email protected]>> Sent: Wednesday, 10 June 2026 07:56:56 To: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> Subject: Re: [PestList] Suggestion regarding pest treatment in an art gallery stationed in Mumbai, India Hi Rahul On the face of it, what PCI Rentokil are suggesting looks sensible, by using chemicals with different active ingredients and modes of action. A classic pesticide users’ approach to IPM. However, true IPM means using insecticides as a last resort. Have they been monitoring already and have they identified possible harbourages, and hot spots of activity. Any proposal to apply insecticides should be based on a thorough survey and monitoring programme first. American cockroaches can equally well live outdoors, especially in hotter climates, so I would be challenging them to propose long term solutions not just quick fixes. Prevention is better than control, so what are they suggesting regarding improved hygiene, exclusion and changes to the building to prevent this problem from developing further or reoccurring. Or are they just wanting to come in and spray? Fipronil is one of the most effective and highly recommended active ingredients used in gel bait formulations to control Periplaneta americana (American cockroach) and Blattella germanica (German cockroach) so not sure why they would say it won’t affect them. The SDS is from Gaiagen which is the sister company to PCI, so is one of their own products. If their own product won’t work (according to them) what other gel baits can they propose? I would still want to see them try the gel bait approach first before spraying anything. Baits need time to work, so this will not be a quick fix. Effective pest management may mean repeat visits. Is this part of their recommendation or are they just suggesting a one-time visit? You mention pantry areas. If you have an area of the building which contains food or is used for food preparation, I would question using sprays in these areas and look at how to improve hygiene here first. For voids in public spaces, perhaps consider treatments such as Diatomaceous Earth or other desiccant powders if available. Any such gaps and spaces should be sealed to prevent insects from using these spaces as harbourages and also to facilitate cleaning. Again, gels will help treat populations that live in ducts and voids as the cokroaches should take the bait and return to the harbourage where they die. It is often suggested that other cockroaches then feed on the dead roach, creating what is known as the domino effect. That was certainly an early marketing claim of brands such as Maxforce. Would they be able to treat these ducts and voids any better with sprays? I hope you find these suggestions helpful. Regards David David Loughlin Historyonics www.historyonics.com<http://www.historyonics.com> From: <[email protected]<mailto:[email protected]>> on behalf of R R <[email protected]<mailto:[email protected]>> Reply to: <[email protected]<mailto:[email protected]>> Date: Wednesday 10 June 2026 at 07:48 To: <[email protected]<mailto:[email protected]>> Subject: Re: [PestList] Suggestion regarding pest treatment in an art gallery stationed in Mumbai, India Hello David, Thank you for this. Pest management company is saying that the gel won't affect American cockroaches which i highly doubt. Also they recommend using sprays in pantry area and draining and ducts, and skirting areas of the viewing space, which I am not sure of. What do you suggest On Wed, 10 Jun, 2026, 12:10 David Loughlin, <[email protected]<mailto:[email protected]>> wrote: Hello Rahul Rentokil PCI are probably the largest pest control service company in India but perhaps not the brightest. They seem to be wanting to throw everything including the kitchen sink at your cockroach problem. If they are proposing to use gels, that is great and fipronil based gel is a decent one to use. However for gels to work, it is advised not to disturb the population by applying any other insecticide, so why they would want to use a repellent and a insecticidal sprays is confusing unless they are treating different parts of your gallery, but even then I wouldn’t. Gels are placed discretely so the cockroaches feed on them, then go back to their harbourages to die. Sprays would disturb this effect. Clothianidin Is a more modern chemical, an neonicotinoid and also used in gel baits but the SDS you supplied is for WDG or water dispersable granules which suggests they want to spray it. Again I would not recommend this alongside gels. It has a broad spectrum effect so will take care of most crawling insects. I wouldn’t allow propoxur anywhere near the gallery. Already banned in many countries, carbamates are old technology and as acetylcholinesterase inhibitors, not great for us. Gumtree are a good Indian company making some decent insect traps so those are fine and I would want to see PCI monitoring the situation. PCI also have access to super sized traps from Gumtree like the Exoroach so that might be worth exploring with them. Hope this helps. Good luck. David Historyonics On 10 Jun 2026, at 06:40, R R <[email protected]<mailto:[email protected]>> wrote: Hello everyone, Recently in one of the galleries, the pest management company saw American and german cockroach in our gallery. Now they are suggesting following chemicals? Are they safe for the art gallery which has artworks. Request you to please advise. Thank you Rahul Raina Senior Manager and Senior Conservator. -- This PestList and the MuseumPests.com web site are made possible due to the talent, intelligence, devotion and donations of hundreds of volunteers. Your donation to help this resource continue would be greatly appreciated. Please consider a donation donating at https://givebutter.com/MuseumPests To unsubscribe from this group, send email to [email protected]<mailto:pestlist%[email protected]> --- You received this message because you are subscribed to the Google Groups "MuseumPests" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To view this discussion visit https://groups.google.com/d/msgid/pestlist/CAG_4n2XM3cWJU9iBZYEoA%2BUoi_1cR2L2Ak2YCNdHtzBkSS8GVQ%40mail.gmail.com<https://groups.google.com/d/msgid/pestlist/CAG_4n2XM3cWJU9iBZYEoA%2BUoi_1cR2L2Ak2YCNdHtzBkSS8GVQ%40mail.gmail.com?utm_medium=email&utm_source=footer>. <Fipronil Gel MSDS.pdf> <MSDS-Bug-Beetle_Guard-_Nov-24__1_ (1).pdf> <MSDS TRANSPORTEX (Propoxur 20% EC) 2021.pdf> <Sumipride CLOTHIANIDIN 50 WDG-MSDS (2).pdf> <GSS Brochure (2) (1).pdf> <Gumtree IMT MSDS.pdf> -- This PestList and the MuseumPests.com web site are made possible due to the talent, intelligence, devotion and donations of hundreds of volunteers. Your donation to help this resource continue would be greatly appreciated. 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