6 replies to this topic

[Foogoo]

- It appears one of my Formica francoeuri pupa forgot to spin a cocoon. Is this common/normal/doomed?

- Is it normal for pupa to spread their legs before eclosing? Or eclose but be motionless for days? I'm wondering if my Dorymyrmex insanus nanitic is dead, though the queen still keeps it with her brood.

 

[drtrmiller]

Ants that spin cocoons generally need some sort of substrate to be able to start the process. If they do not start spinning, I suppose harm or abnormal development is possible, but I can't point to any direct evidence of this, as I've had ants develop properly without spinning one.

 

If an ant is dead or defective, the other ants will either recycle or discard it.  No action is required on your part.  Just let the ants do what they do.

[Miles]

It is not uncommon for some formicine larvae to fail to form a cocoon. This is often thought of as being a result of a lack of substrate in the founding chamber. This is one of the reasons that I don't like test tubes as a founding option.

The pupae in your picture looks like it is eclosing.

 

Edit: I did not see Terry's reply above, so my post is somewhat redundant.

Edited by Miles, May 16 2015 - 7:22 PM.

[Mercutia]

My Formica do just fine spinning cocoons in a test tube. Even in other setups with substrate sometimes they won't spin cocoons. Sometimes I get Formica who refuse to spin cocoons at all. Sometimes I get a mixed brood of naked and cocoons. Sometimes they are all cocoons. There are no problems with naked pupae. They eclose just fine. I've never had any problems with naked pupae eclosing.

 

There are a lot of factors why they sometimes won't spin cocoons. Substrate is a very very small factor and I find don't usually affect whether they spin or not.

[dspdrew]

I find Formica in the wild with lots of naked pupae, so it seems perfectly normal, and probably outside of your control.

 

Even when I collected brood from one of the Formica francoeuri colonies at Mormon Rocks Station, half their brood was naked.

[Foogoo]

Interesting, thanks!

[Trailandstreet]

I had a few lasius and a Formica in test tubes and they all were able to spin cocoons. i guess, it is not the only factor.