Cecropia Moth Rearing - Request Help

Matt Smith MatSmith1 at compuserve.com
Fri Jan 9 17:55:33 EST 1998

On Tue, 6 Jan 1998 19:03:51 GMT, donald.davis at utoronto.ca wrote:

>A friend of mine in Britsh Columbia requests help in identifying the
>cause of lethargic behaviour with Cecropia moth larva.
>Has anyone out there experienced any of these situations before to be
>able to suggest a cause? Is it viral? Environmental?

Its a long time since I have reared any kind of silk moth but I have
had some similar experiences with various species, though
unfortunatley I cant remember which.

>In one case, the larvae seemed to lack ambition from the start - to even
>move from old leaves to fresh ones. Most died.
Sometimes this does seem to happen with some broods, for some reason
they dont get going and end up as "poor doers".

>On another occasion, the larva were fully developed and just stayed on a
>branch for a few days before dying.

Sounds like a virus infection,  did the larvae end up going brown or
black and hang from the twigs by one or two claspers.  If so, remove
any infected larvae and sterilise the whole cage as soon as possible
with bleach or baby bottle sterilizer

>In a third case, the larva simply remained on the floor of the cage as if
>dead. They eventually formed a chrysalis but didn't spin a cocoon first.
I would think moths pupating on the cage floor without spinning a
coccon would be due to environmental factors, ie disturbance when
spinning.  If larvae are disturbed or moved when they have just
started to spin there doesn't seem to be a problem.  However, if they
are interfered with towards the end of their spinning (eg they have
spun up between the cage door and cage side and the opening of the
door destroys the cocoon) then some of them wont start to spin a whole
new cocoon again.  Presumably they have gone past the point in the set
of inbuilt cues that says "is this a good site - spin cocoon" and
can't get back to the start of the sequence as they can do if they are
stopped at the start of the process.  Either that or they have just
run out of the components required to spin silk.  Either way, if you
have any old empty cocoons, pop these larvae inside and they seem to
pupate and hatch ok if you treat them as normal.


Matt Smith

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