Yellow caterpillars in old bees nest

[Matthew Smith]

Message text written by INTERNET:billgrange at billgrange.demon.co.uk
>I have just had a number of yellow caterpillars brought by an enquirer
into the museum where I work. They were inhabiting a plant-pot which was
previously colonised by bumble bees.  The caterpillars are about 1.8 cm
in length, with well developed 'true legs' and four pairs of 'false-
legs' or 'pro-legs' (so I assume they are moth, rather than sawfly). The
segments are very distinct. The body coloration is a strong yellow, with
a brown head - no other obvious markings. The most remarkable thing is
that they have constructed a silken mass of extremely tough silk,
consisting parallel-running cylindrical cells.  

I would be extremely grateful if anyone could offer an identification.

I am in Great Britain
-- 
Bill Grange
<

Your description of the silk tubes, plus the fact that the flowerpot used
to contain a colony of bumblebees, suggests that these caterpillars are
larvae of the Wax Moth or Bee Moth - Aphomia sociella.  The eggs are laid
in the nests of honey bees or bumblebees , they are also reported from
combs of social wasps. 

The larvae live in a group and spin tough silk galleries or tubes.   I've
only seen them myself on old honeybee combs, they make their tubes in the
centre of the comb and the bees find it vey difficult to get to them.   A
severe infestation can do a lot of damage to a honeybee hive, though
usually the honey bee does a good job of keeping them out. The caterpillars
initially east scraps of wax and rubbish, but when large enough will
destroy the whole bumblebee nest, eating wax, stored pollen and even
bumblebee larvae.   When mature the larvae leave the nest in a group and
spin tough cocoons to overwinter.  The larvae are described as yellowish,
sometimes with olive green on the back.  Unfortunately the moth is a rather
drab creature and not vey exiting to look at.

Regards

Matt