Sad Demise of the Lasius umbratus Colony

As summer draws to a close and Autumn begins to show itself, here’s an update on my colonies.

Lasius umbratus

Today on checking this colony, I saw what appeared to be an empty nest. But no, wait. There’s the queen moving about in one of the chambers. Sadly, there appears to be just one worker with her. I put some food in for them and the lone worker examined it. However, she did not seem to pay much notice. As hard as I tried I could not see any other ants, or even brood. For all intents and purposes this colony is reached its end.

12 years ago that I obtained this colony as a newly ensconced Lasius umbratus queen, with 30 Lasius niger workers. Over the following two years the queen laid eggs of her own kind, whilst the niger workers naturally died out. This queen went on to produce a flourishing umbratus colony with thousands of workers over the next 10 years.

Sadly, such as is inevitable, the queen came to the end of her egg-laying days, and the colony started to dwindle in size. I cannot see the queen or her lone worker lasting to the end of the year.

What will I do with the nest? I do not plan on obtaining anymore colonies. What I thought might be fitting is to return the colony to that of Lasius niger. The original colony would have been Lasius niger before the umbratus queen took over. Now the niger can have the nest back. I will probably attach it to the current Lasius niger set up, once the umbratus queen dies. In the wild Lasius niger often invade the nests of Lasius flavus, a more skilled nest builder. The niger then move in to the new home. It’ll be interesting to see what my niger will react when they see the abandoned umbratus nest.

Lasius niger

This colony is really starting to flourish now. When I put food into their foraging tank it is quickly over run with ants. I gave them a live sun beetle larvae the other day and they quickly subdued it before killing it. They then cut it up and took it back to the nest to feed the queen and other workers.

They seem to be able to kill the sun beetle larva faster than the Myrmica rubra do. However, I think this is a case not so much of the niger killing it quicker than the rubra. It is probably more due to the fact that the niger use a paralysing (formic) acid to subdue their prey. It probably only appears to be dead.

There is evidence of nest expansion by the deposits of sand in their foraging tank. Peering inside the nest I see new tunnels. Though they tend to keep their brood on the surface of the soil in the nesting box. Because the nesting box is completely covered in dark cloths, the ants treat the surface of the soil as another chamber. I could not see the queen, but she is in there alive and well by all accounts.

Myrmica rubra

2021 has been this colony’s best year so far for population growth. I put this down to the increased food allowance I have been giving them as I copy Dermy’s old idea of his dermestid “over-feeding challenge”.

There have also been record numbers (for this colony) of winged males and females being produced. I am also sure that one of the winged queens had removed her wings. A wingless queen has been walking about, who looks slightly different from the queen I am used to seeing. Has she mated? I do not think so as the only males present have been her brothers. Unless, and this is an incredible long-shot, a Myrmica rubra male from another colony has found my captive nest. But, no, I will have to dismiss that idea as being ludicrous.

Lots of brood and nest expansion seen over the course of this year.

4 thoughts on “Sad Demise of the Lasius umbratus Colony”

  1. Hi Myrm,

    Glad to see you still posting updates. It’s a shame to hear about the Umbratus colony but I think they had a good run!

    All the best,
    Drew

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