Swarm absconds and abandons brood

[Rurification]

I had a small swarm on June 2nd.   Caught it, boxed it.   Slow to get going, but then was laying like a dream.   Yesterday they absconded.   I caught it and put it in a nuc [didn't realize until later which colony it was.]   

When I checked their old box, there were 3 frames full of BIAS - just abandoned.  Also some cells with multiple eggs at the bottom.   No honey.  We're just at the end of the flow. 

What would make a colony abandon that much brood?   

Are they worth keeping?   

[iddee]

Same as you would. If you are hungry, you will go looking for food. That's what they did.

[Rurification]

I understand, but we're not in a dearth.  We're just at the end of the summer flow.  Everyone else is still bringing in honey. 

Are they worth keeping?

[iddee]

Less than 3 lb. of bees, NO.  More than 3 lbs, YES.  Feed heavily

[cao]

Are they worth keeping?

My cut off would be if they could get to 3 five frame medium nuc boxes full by winter.  I overwintered two hives like that last winter.  Anything less than that, I haven't had any luck getting them through the winter.  And yes I would feed them.

[Rurification]

Thanks for the feedback, guys!   

I took out their old frames and put them back in their box with a frame of new brood and a frame of empty drawn comb and started feeding them 2 quarts of syrup from a medium above. 

I've had good luck overwintering single boxes with sugar bricks and a quilt box on top.   This queen is a good layer.   It is still July [barely] so they've got some time and we have a decent fall flow.   We'll see if she can fill a box. 

[jalentour]

Go for it, you have little to lose.
I'm a little south of you in the Ohio River Valley, no sign of dearth, but it will be here for sure.
Feed a lot.