Cacoxenus indagator, a cleptoparasite of red mason bees video

June 20, 2014

in A selection of my garden wildlife videos

Cocoxenus indagator, a ‘fruit fly’ that starves some solitary bees to death

You may see these little ‘fruit flies’ around your red mason bee nest boxes. This feeble flying insect is no fruit fly as a larva. It is a cleptoparasite . They are opportunists and literally hang around watching and waiting. They are looking to sneak into an empty cell, check it out to see if any pollen has been stored. If it has, she will quickly lay some eggs and leave pretty pronto before the host bee returns. The resulting larvae eat the pollen store and in many cases if there are simply too many of them, the bee larva will starve, usually to death. I have found up to ten larvae in one cell.

Cocoxenus indagator Nurturing Nature

How do the adults escape from their cell? I have the answer…… coming soon when I edit it!!


Thanks to Iwan Edwards, Community Wildlife Officer, North East, North Wales Wildlife Trust who kindly donated the Cacoxenus indagator fly larvae and frass to make this film! Only happy to help he said!  I wonder why! This year though I have my own!!

{ 2 comments… read them below or add one }

Marian June 20, 2014 at 2:11 pm

So interesting George, look forward to seeing the escape!! Hav’nt seen any around my boxes, but no doubt they are there lurking. Saw a small fly yesterday around my boxes, bright turquoise In Colour with an orange rump. About 1/2″ in size. Have never seen this before and have looked through my books of knowledge but can’t find any reference. It was the colour I was drawn to. Any idea?

Cheerio for now


nurturingnature June 20, 2014 at 10:12 pm

Try ruby tailed wasp Marian, another red mason bee trouble maker! Cheers George


Leave a Comment

Previous post:

Next post: