cecropia larvae

[Lisa Larson]

Hi, I'm rearing cecropia for the first time and have a couple questions
about a few untimely demises.  I have about 15 larvae; they're about
fifteen days old, and are in their first and second instars (they
hatched over a period of about a week, not all at once).  I've been
feeding them lilac leaves which have not been treated with any sort of
pesticide.

Today three first-instars were dead at the bottom of the container.
There was some murky liquid around them which they may have exuded while
dying, or may have drowned in.  The leaves I put in last night were a
little damp from rain-- I figured the caterpillars would be adapted to
deal with that, but maybe some water pooled up and they just drowned?
Or could some disease have afflicted them, despite their being indoors?
Or should I just expect this sort of mortality rate?

Thanks,
Lisa