Beware of things that fluoresce. Urine (rodent and other kinds) fluoresce when activated by light in a range of UV wavelengths. All things that shine, however, are not urine. Cotton fibers will shine brightly, as will most kinds of white paper, many kinds of construction adhesives, cleaning agents, and more. In many cases, you may encounter constellations of splotches, drops, trails, and more. The mouse urine might be the least prominent component. For more guidance see: https://www.pctonline.com/article/-copesan-university--using-a-black-light-for-a--rodent-inspection/
One trick is to clean and assess the site so that you know the baseline fluorescence, then monitor for changes (new stars / moons) thereafter. Alternatively, you could lay a few sheets of dark paper (that you’ve checked for fluorescence) and monitor those with a UV lamp. There are specialty papers that can be useful to detect urine droplets and document trails, but those are impractical in many situations. Most importantly, be careful with UV sources. Some are safe for viewing with unshielded eyes, and others require the right kind of goggles to protect eyes. Hope this is helpful. Rodents have not, as yet, been carrying around UV lights or lasers to detect or confuse people. Let’s hope that doesn’t happen anytime soon. -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 [A blue and black logo Description automatically generated]<https://www.linkedin.com/in/richard-pollack-6818997/> From: 'Ritchie, Fran E' via MuseumPests <[email protected]> Date: Tuesday, January 20, 2026 at 1:17 PM To: [email protected] <[email protected]> Subject: [PestList] Is this mouse urine fluorescing? Hello! I’d like to use the attached photo as a reference photo when training people on IPM. I think that it’s mouse urine fluorescing yellow under a UV flashlight. The fluorescing trail appears to be tracking from a crevice between the bottom shelves of abutting shelving units. I took the image 4 years ago when we had a mouse in our facility. We saw droppings in the area (they had already been cleaned by the time I brought in my flashlight, so I can’t confirm they were in the same spot). And the area smelled like urine to me. But I don’t have known mouse urine trails to compare this image to. What do you all think? Could this be urine, or is it more likely an unknown substance that happens to fluoresce? Thanks! Fran Fran Ritchie, Conservator (Objects) she/her Harpers Ferry Center [email protected]<mailto:[email protected]> American Institute for Conservation Professional Associate (peer-reviewed) NPS Conserve O Grams - Museums & Collections (U.S. National Park Service)<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nps.gov_subjects_museums_conserve-2Do-2Dgrams.htm&d=DwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=GO7C3XN3WgFy2IP-bFBbnUs_CYntqj57Dprtl40-_KE&m=HhB1UnPHDK0txdwjVbK5uJ_LydaA1fBRecibXhvZgIq_Uvs0x2vHoF4SZn1IJv4E&s=KFupCkMCoQafX1WayXesRLB6wvzGfvvAoPoBhFbD6jA&e=> -- 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<https://urldefense.proofpoint.com/v2/url?u=https-3A__givebutter.com_MuseumPests&d=DwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=GO7C3XN3WgFy2IP-bFBbnUs_CYntqj57Dprtl40-_KE&m=HhB1UnPHDK0txdwjVbK5uJ_LydaA1fBRecibXhvZgIq_Uvs0x2vHoF4SZn1IJv4E&s=aqmMyyciCNkg9URWCBIEas92tk9LZ5seMAOxzJdhpJo&e=> To unsubscribe from this group, send email to [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/PH0PR09MB8777F3B6A2FE2F27D7948B09EB89A%40PH0PR09MB8777.namprd09.prod.outlook.com<https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_msgid_pestlist_PH0PR09MB8777F3B6A2FE2F27D7948B09EB89A-2540PH0PR09MB8777.namprd09.prod.outlook.com-3Futm-5Fmedium-3Demail-26utm-5Fsource-3Dfooter&d=DwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=GO7C3XN3WgFy2IP-bFBbnUs_CYntqj57Dprtl40-_KE&m=HhB1UnPHDK0txdwjVbK5uJ_LydaA1fBRecibXhvZgIq_Uvs0x2vHoF4SZn1IJv4E&s=9dSSnYqqR4HI9rBkMoGbnoTUHr57OrlLNm83Y1W5fqs&e=>. -- 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] --- 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]. To view this discussion visit https://groups.google.com/d/msgid/pestlist/MN2PR07MB7839538B482E8A2E2A8192A09489A%40MN2PR07MB7839.namprd07.prod.outlook.com.
