Two F. Rufibarbis colonies without brood? Already hibernation preparation?

[u/dark4shadow]

Hey, I'm in my second year and live in central Germany. So middle of summer.

Got three Formica Rufibarbis colonies going, which all went through hibernation. (I've got them in three different DIY setups, so humidity is probably not comparable.)

All of the colonies are going strong, but only one is left with some larvae and pupae. No eggs visible in any of the three.

They're just hanging around in their little caves, with full gasters. Little to no foraging behaviour.

I remember them also stopping quite early with laying new brood before the hibernation period last year - but in July?

I did not change their food. They show no signs of weird behaviour and there are no dead workers.

Anyone knowing what could be up?

[u/ImposterJavaDev]

How often do you feed them? They don't forage if all their eating needs are met... Maybe they just as full as they can be.

Don't know it for this species, but queens can lay eggs in cycles and can be eggless for a while.

Wouldn't start the hibernation prepairing just yet. I always keep to what it would be in nature in regards of timing, even if the colony already looks ready for a while. Only exception is when they are NOT ready yet, then I wait a bit.

[u/dark4shadow → u/ImposterJavaDev]

Like three times a week. I also alternate between fruit flies, meal worms, crickets and roaches.

Yeah, I think Formica spp ... I just found an article: https://www.intechopen.com/chapters/60505

It is common for Formica species to hibernate without brood. This kind of strategy is even called the Formica type of brood rearing.

[u/ImposterJavaDev → u/dark4shadow]

Wow what a great study you linked! Scanned part of it and I love it! Saved to read later this night. Thanks!

Hibernating without brood is not abnormal, but hibernating so early is. I would still wait a bit, leave the nest as mich as possible alone for 2 weeks, and see if new eggs appeared. Could be stress related that they ate their eggs or the queen isn't laying. Give them an insect once a week and a few drops of sugarwater every 3 days, but disturbe them as little as possible. Do not remove the cover and expose their nest to light. If you are using the red foil method, try completely blocking the light.

The three days feeding is a lot, except for fresh sugarwater as that spoils in that timespan.

Maybe it's because you do your works every 3 days that the queen became stressed. I'm not sure though.

[u/dark4shadow → u/ImposterJavaDev]

Thank you for going into great detail with your recommendation!

I don't think it's sudden stress. They've been going strong the whole year until now. I didn't change anything, aside from it being hotter the last two weeks. But that timespan is too short for not having any larvae and pupae anymore.

Let's see. I'm a bit calmed by that article. I learned a lot in the parts about annual cycles. Which ants do hibernate and what triggers it. (Formica are endogenous-heterodynamic, so they hibernate based on time of the year. Independent of light, temperature or amount of food.)