Re: Will a luna caterpillar winter over if is is raised indoors?

Hi Phylicia,

I understand that your message has been waiting for a response for some 
time now, so maybe your caterpillar already answered your question.  If 
that's the case, it'll be interesting to know if the experts I talked to 
were on the mark.

First I have to start with a few clarifying comments, just to make sure 
we're both thinking and talking about the same situation.  Like all 
butterflies and moths, luna moths go from egg to caterpillar to 
pupa/cocoon, to adult.  Each stage has a general 'life span', which is 
determined by lots of different cues, including environmental conditions 
such as temperature and photoperiod, or light cycle.

So, thinking about luna caterpillars....  Lunas won't overwinter as 
caterpillars.  Instead, they overwinter as pupae, or cocoons.  In the wild 
and indoors, luna caterpillars eat and eat and go through stages called 
instars.  There are a defined number of instars each species goes through, 
and then it's time for them to pupate, or build their cocoons.  Even if 
they have enough food and they're warm and snug, caterpillars will 
eventually pupate at the end of their last instar.

Cocoons need cold temperatures and shorter photoperiods ("daylight" hours) 
for overwintering.  Extended stretches of cold weather and short days 
basically tell the critter to hang tight in the cocoon until it's nice 
outside again.  During that time in the cocoon, the animal is developing 
into an adult.  Then the days start to get longer and warmer, and that 
signals the lunas to emerge from their cocoons as those gorgeous green 
moths that always take my breath away.

If you find yourself with a luna caterpillar and it's getting to be 
wintertime, you have a few choices.  You can leave it alone to go through 
this process outside 'in the wild', or you can bring it in and allow it to 
pupate.  If you do bring it inside, I recommend keeping it in a jar with 
holes in it, mainly so it can't escape and so you can watch it go through 
these cool stages.  

If it's about ready to pupate, you're all set.  It'll spin its cocoon and 
then it's time to wait.  Put it in a protected area, either in a garage or 
outside on a windowsill or something like that.  Since you're in Georgia, 
where it doesn't get too super cold, I'd put it in a windowsill where it 
will be exposed to regular light and temperature cycles.  Be sure to keep 
an eye on it regularly, so you know when it emerges.  You don't want to 
trap it in the jar forever (I hope!).  When it gets all the signals that 
say spring is here, it should emerge and you can let it go to start the 
whole life cycle all over again.

Luna moths are among the most amazing animals I've ever seen - their 
antennae are absolutely spectacular, and the color and shape of their 
wings is unreal.  Enjoy your encounters with these great animals.

-- references:  Personal communication with keepers and curators at the 
Woodland Park Zoo, The Toledo Zoo, and Sophia Sachs Butterfly House.