Why do I find dead bees in all my Mandevilla's flowers. I do not spray with anything.
This may be just a naturally occurring event, instead of something sinister.
Bee's live really only a short period. Queens are the longest living bees.
They may have lived out there lifespan and simply died.
Keep an eye out for any other signs of unusual Bee die off.
You can report large numbers to your local County Extension Office.