Hatching of praying mantis cocoons (2nd posting)

Paul S. Winalski winalski at gemcil.enet.dec.com
Sat Oct 15 16:56:08 EST 1994

In article <Cxpo5s.HxG at world.std.com>,
rp at world.std.com (Richard Pavelle) writes:
|>I bought some praying mantis cocoons in the spring and most had
|>hatched by July. Recently, I cut open up one of the cocoons that 
|>had not hatched, and it is filled with larvae.
|>Can someone tell me why they did not hatch? What determines
|>whether it will or will not hatch. Might it hatch if I keep it
|>in a warm place now or are the larvae likely dead? 

First off, what you have is a praying mantis egg case, not cocoon.  Mantids
don't have the classic 4-stage insect life cycle.  Instead, they lay eggs
imbedded in a hard, styrofoam-like mass.  The eggs hatch into juveniles that
are like miniature adults.  They gradually transform to the adult size as they
grow.  There is no separate, dormant pupal stage and hence no cocoons.

My only experience with mantid egg cases involves one that I harvested in
the fall (I lived in Connecticut at the time) and kept in an unheated room
over the winter.  One day the next spring, all the eggs hatched nearly
simultaneously and there were dozens of the little creatures.  At least with
the northern US species, I suspect that they need the cold-to-warm temperature
transition from winter to spring in order to trigger the hatching process.

It's most likely that the eggs that didn't hatch by the fall are dead, but you
might want to keep them outdoors over the winter and see if they hatch next
spring.  You wouldn't want them to hatch right now, anyway, as the cold of
winter will kill them in a few weeks.


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