Mystery Death of “Magenta” Colony

As readers of my journals may know, I have a 4-year-old Lasius niger colony (the “Magenta Colony”) which I have raised from a single queen ant captured during the mating flights of 2015. As is normal with new Lasius niger colonies, the growth was slow for the first year, picked up in the second, and exponentially grew in the third and subsequent years. All was going well this year, until …

Last week I awoke and checked on my ants as I do every morning. To my chagrin I discovered that every single ant in this colony had died. Overnight! Every single ant! They were laying in the main chamber of their nest. The queen too. I have absolutely no idea what happened here. They are fed with the same food and water as my other two colonies, and they nest in the same type of substrate. Their nest is in the same room, on the same worktop as the other colonies, within a few inches of each other. Yet, the other two colonies are fine. Though, saying that, I do believe that the Lasius umbratus queen did not survive the hibernation period this year, as I have not seen any sign of her, and there is a marked decrease in the number of workers present.

Is the death of the umbratus queen and the entire Magenta colony related? No, I do not think so; I believe they are coincidental. The umbratus queen was in her 11th year, and these queens live, on average, 10-15 years. So, she was in her twilight years. I was expecting this to happen sooner or later. However, the Magenta colony death has me perplexed. It was the speed at which they all died that has me mystified. Something has obviously happened, but what? Disease? Maybe. In fact, it’s the only reason I can think of. If it was the environment, food or water then the other colonies would have met with the same quick fate, surely?  It’s a complete mystery.