Cannibalistic Monarchs???

[JD Micro]

I have been breeding and raising Monarchs in large numbers for 3 years now.  In
my first (inexperienced) year, I observed 5th instar larvae cannibalizing newly
formed pupae in an overcrowded cage.  I assume this was directly related to
overcrowding since thinning the numbers of larvae per cage seems to have
eradicated the behavior.  It is interesting that the hardened older chrysalides
were untouched. 

I have not personally observed larvae consuming ova but I normally have
discrepancies between the number of ova collected and the number of larvae a
week later.  I'd estimate a loss of about 10-15%.

It's an interesting concept...deliberately eliminating future competition...if
you find any research on it, please let me know.