Sunday, 5 May 2013

Caterpillar eats orchid

Serapias labellaThe tongue orchid produces no nectar.   Yet in the tubular hollow formed by the petals one can  find from time to time insects of various kinds.  Tiny beetles can scurry around.  Nevertheless it was something of a surprise to find a caterpillar (May 3rd 2013)  The caterpillar was tiny but the space is small and it was curled up. Its head was moving up and down as though it was eating, and indeed that was the case!
T=he flower of this orchid has a bright shiny purple swelling  on the labellum. That is to say the petal which lies lowest
and forms the base of the flower tube.  I extracted the caterpillar by shaking onto a small saucer and dissected the flower.  In the illustration here I have pinned the labellum of the eaten flower next to another which was not eaten.  You can see how the caterpillar has chewed at the red swelling in the petal on the left, exposing the pale tissue beneath.
Pursuing this matter, I searched for the species name of the caterpillar.  To keep it alive so I could see it more easily  I placed it on another Serapias flower head held in some water in a glass beaker.  The caterpillar crawled up the flower and proceeded to eat at the edge of a petal in the fashion which is common to caterpillars, attacking the petal edge sideways on and champing through as though it were a leaf edge.
The next two pictures show the caterpillar at the top of the flower and beginning to feed.

It appears to be the caterpillar of the common quaker moth [Orthosia cerasi syn - O.stabilis]  The books give the food plants as oak, elm. birch, willow, hawthorns, hazel and perhaps others.  I think I can add Serapias lingua!
The most likely explanation for thecreature being on the orchid is that heavy rain and gusty winds which have shaken the  'darling buds of may'  have thrown the caterpillar from the young leaves of the downy oak (Quercus pubescens) which are above this little group of orchids and the little creature will happily eat whatever it can.
The Common Quaker Moth is not that spectacular.  Its  fore wings are brown but prettily patterned.