Cannibalistic Monarchs / part II

[RENE BOUTIN]

In the hundreds of monachs I've raised or had kids raised them,in two occasion I
saw a  devoured pupa by another caterpillar
                                                       René Boutin

"Martha V. Lutz & Charles T. Lutz" wrote:

> Hi . . . me again.  My original note got this response:
>
> ///> Can anyone confirm (or refute) for me that Monarch larvae will eat
> > conspecific eggs?  A few years ago while raising Monarchs I lost an egg.  I
> > thought I had miscounted eggs, or perhaps misplaced one, or maybe the kids
> > took it out and didn't put it back.  I thought about that disappearing egg
> > today--when it happened again.
>
> I know whereof you speak.
>
> There a number of other possibilities.  Lacewings (probably either adults or
> immatures) and coccinelids (ladybugs, also probably either adults or immatures)
> come to mind right off the bat.  I had a couple hours-old hatchling gulf
> fritillary caterpillars (and one less than an hour old) a couple years ago and
> lost both them an some eggs on host plant (pssion vine foliage).  On checking
> them the afternoon after I had captured them, I found one nice fat lacewing
> larva and no caterpillars or eggs.  I was not a happy camper.
>
> Pierre A Plauzoles
> sphinxangelorum at bigfoot.com
>
> ///
>
> It's a great hypothesis!  But I should have mentioned (sorry I left this
> out) that the Monarchs were the only living things in the cage, so I can
> rule out predation other than by the one larva on the same leaf.  I have,
> in the past, lost various Saturniid larvae to spiders that rode in on the
> twigs I used to feed the caterpillars, but with these Monarchs I was using
> single leaves, and had looked them over pretty carefully first.
>
> Another possibility I thought of was that the egg was sterile and simply
> collapsed to the point of invisibility (although I did look for
> it--unsuccessfully--under a low-power magnifying glass).  Today I swiped
> the egg from a newly-hatched Monarch and took a good look at it . . . there
> was nothing I saw that looked like that eggshell after egg #1 vanished.
>
> I hesitate to simply conclude that there is cannibalism among Monarch
> larvae, but I can't rule it out at this point, either!
>
> Does anyone have any more information on this?
>
> Since Saturniids are not cannibalistic (not mine, anyway), it does raise
> some curious evolutionary ideas about Monarchs.  There are some interesting
> possibilities concerning the selection pressures that would produce this
> behavior.
>
> Thanks!
>
> In Stride,
> Martha