Wednesday, September 19, 2012

The weevil within

The hollyhock seed pods are drying up now and rings of holes have become visible around many of them.  I was not surprised to see these holes, since in the past weeks I have seen many bugs feeding on the seed pods.  What did surprise me was that quite a few holes had something protruding out.

Something is sticking out of one of those holes in the hollyhock seed pod.
Intrigued, I began peeling open a pod.  Inside, in addition to the hollyhock seeds, I found a large group of hollyhock weevils (Apion longirostre).  Once exposed, the weevils quickly dispersed in search of cover.

A hollyhock seed pod full of hollyhock weevils (Apion longirostre).
How had all those weevils gotten inside the seed pod?  Through holes -- but not the holes in the seed pod.  There were matching holes in the seeds themselves, and not all these holes were empty.  Several had the long snouts and antennae of yet more weevils sticking out.  I broke open the seed pictured below to reveal the weevil that had grown inside.

A hollyhock weevil (Apion longirostre) developing inside a hollyhock seed.
Earlier this summer, a female hollyhock weevil must have laid her eggs in the ovaries of the flower.  As the seeds developed, so did the weevil larvae, consuming the seeds from within before pupating and finally emerging as adults.

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