Melittobia acasta is a parasitoid of solitary bees

When I saw this, I was amazed at the tiny size of the gap that this determined parasitoid wasp was in entering the mud sealed nesting cavity of a Red Mason (Osmia bicornis) bee. If left unchecked it and its offspring can wipe out all of the bees not only in this one cavity but the whole nest box, enough justification for me to replace the complete inner nesting unit with a fresh one for the summer bees that also use the nest box.

One of several parasitoid wasps that can devastate your solitary bees

Red Mason bees are spring bees, and many more species arrive early summer-late summer depending upon species. Many pests relish and indeed target such provisions, the pollen, egg or bee larvae that are in your nest boxes. I have replaced the nesting unit, and stored it out of harm’s way!

For more information about Melittobia acasta with video

 

Apologies for the out of focus film. I was not wearing my glasses!!

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