I am quite confident that I have a swarm of Red Mortar Bees in my porch roof. Used this site to identify them.
When I use the hedge trimmers or strimmer near them they all come out of the nest. It's quite scary. Is it true that they are harmless? Could I just carry on gardening and not be attacked by them?
The bees are about 1cm. I've tried to get better pictures but I am very nervous when they start swarming around me when I get close.
Well, I'm not an expert but they don't look like red mason bees (is that what you mean by red mortar bees?) to me. They look too slender, not hairy enough and the antennae are too short. But I wouldn't like to say what they are. They're the right shape for honey bees but their abdomens are a uniform colour. Is that a honey basket I can see on the third photo?
Wait to see if anyone else replies, but if they don't then I can only suggest you get a good photo of one and post it separately to this discussion.