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Entomology (Study of Bugs)/Ants on toilet ceramic


QUESTION: Hello good day sir!

I am Nurul Raihana from Selangor, Malaysia. Currently we are facing el nino phenomenm here where its hot and sunny all the day. This situation is predicted to last until March 2016.

Recently I noticed, there are bunch of ants (black ants-not biting) in my toilet, and most of them 'stay' in toilet sink which made of ceramic. Some stayed around toilet bowl. Some on floor tiles. Firstly I tought theyre eating the left of toothpaste or mouthwash, but as I look down closer, they are more likely in resting position - put their back down and they dont move like they're taking a nap.

Well, just get tiref when everytime  haveto save them from drown in water splash. I don't want to kill them as I respect them as the most hardworking and cooperative team creature. I just blow so they can wakeup and move to use my toilet sink. and they will gather back at same spot after a while.

My question is, why do they behave like that? Don't they feel insecure to stay outside of their house - to be in a place that always be used by human. Is that related to the weather?

Thank you in advance for your respond.
Terima kasih :-)

p.s Disabled to upload picture. Something wrong with this website

ANSWER: Greetings, Raihana - Without being able to see some images, I can only speculate. Ants, like many other insects, usually congregate for specific purposes/response to stimuli, such as food, water, shelter, environmental factors (such as shade, temperature, or relative humidity), mate finding, etc. Also, as most ants rely heavily on chemical communication, they may be attracted to some chemical cue found in your bathroom.
Hope this helps a little,

---------- FOLLOW-UP ----------

QUESTION: Thank you for your respond.

Is that possible they are lost of their pheromone trails? Maybe the trails washed away since they're congregate in the bathroom

I would consider that only if you had noted them trails of them earlier in other areas of your dwelling where they would have to had traveled through your bathroom in order to get there. My primary suspicion is that there is some chemical cue in your bathroom that they are responding to.

Entomology (Study of Bugs)

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Ed Saugstad


Will accept most questions in general entomology, including those related to medical entomology, taxonomy, ecology, arthropod surveillance, and pest management. If you are requesting a 'mystery bug' identification, PLEASE either attach an image to your question, or post an image on a web page (such as Flickr) so that I can look at it, as verbal descriptions frequently are insufficient for a definitive identification.


21 years in the U.S. Army as a medical entomologist; duties varied from surveillance of pest populations (including mosquitoes, cockroaches, ticks, and stored products pests) to conducting research on mosquito-virus ecological relationships and mosquito faunal studies. Ten years as a civilian analyst for the Department of Defense, primarily on distribution of vector-borne diseases worldwide. Limited experience on surveillance of agricultural insects in North Dakota and Indiana.

Entomological Society of America, West Virginia Entomological Society, Society for Vector Ecology, National Speleological Society, West Virginia Association for Cave Studies.

American Journal of Public Health, Contributions of the American Entomological Institute, Japanese Journal of Sanitary Zoology, Journal of Economic Entomology, Mosquito News, and Mosquito Systematics.

B.S. in entomology from North Dakota State University in 1963, M.S. in entomology from Purdue University in 1967.

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