why caterpillars eat their eggshells

[Anne Kilmer]

Because they're there. 
Some butterflies coat their eggs with noxious chemicals ... those with
scent pockets on their wings do this. Monarchs, tropic queens and such.
Ants do not care to eat such eggs. 
Were I exploring such things, I would wonder whether the chemical-laced
shells therefore help protect the infant caterpillar from such
predation. 
Pretend the question is phrased "why do caterpillars benefit from eating
their eggshells", and the responses will seem less tautological. 
I was told, as a novice butterfly farmer, never to roll the eggs off the
plants to take home and rear (as Butterfly world does) because if the
egg is lying around loose, the larva is likely not to find it and eat
it, and may therefore fail to mature properly. 
Take the leaf the egg's on, they said, or stick the loose egg to a host
plant with a small quantity of egg white. I haven't tried that, and I
don't want to. It is easy to staple the eggy leaf to a host plant. 
But Butterfly World's butterflies look just fine, so I wonder whether
this is foolish superstition, or whether they are rearing the eggs is
such sterile conditions that ants aren't a factor. (one assumes so.)
I'm sure somebody actually knows, but the answer is going to be all
dressed up in long words and hidden someplace amateurs don't want to
look for it. 
Anne Kilmer
South Florida
 


Cris Guppy or Aud Fischer wrote:
> 
> The first step in answering the questions might be to ask "Why do some
> caterpillars eat their eggshells, and some do not?" Caterpillars of some
> butterflies definitely do not eat the eggshells (chorion), others eat them
> sometimes or only partially, and some species always eat the entire
> eggshell. I have no idea what the answer to the question is, other than
> having previously read the assorted speculations that have been repeated in
> various postings in this thread. And of course there may be more than one
> answer, with different butterfly species eating (or not) the eggshells for
> different reasons.
>

 
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