I had two small colonies of Lasius flavus ants. The first one was about 1.5 years old, but it developed really slowly, with only 20-25 workers present and one queen.
The second one was only 7 months old and initially had two queens, one of which was killed by workers. It had about 15-20 ants. Both colonies finished hibernating about 1 month ago.
Recently the queen of the second colony died of no apparent reason, while all the brood and workers were alive.
So I decided to introduce them to the first colony using the freezing method.
The "orphan" workers were put in fridge at 5-8 oC for 2 hours, and then introduced to the first colony one by one. At the same time I put some sugar water in. Flavus ants are not aggressive, so they didn't start fighting immediately, but once all the brood and workers were introduced, the "host" worker ants started pinching the newcomers. At the same time, all the brood was accepted.
I put the test tube in the fridge at 5-8 oC for 3 days. After warming up the workers seemed to calm down completely. After 3 days of staying at room temperature there is no dead workers and all the brood is present.
Now there are about 35-40 workers and one queen. So the freezing method works well with small L. flavus colonies.
Pictures of the final colony:
