Do you live in an urban area or the countryside?

We live pretty much in the centre of London, so I'd say urban! We have jasmin, mock orange, a greengage tree, heebees and roses in the garden.

Youngster of a lady beetle. A good guy. They eat aphids.

In the centre of London I'd say this is quite unusual. It may be that some spores have found their way into your garden from muddy boots or wellingtons. Have you been rambling at all?

Also, I would consider chopping down your greengage tree as it can have a propensity to shed fruit, which could potentially cause injury.

Ladybugs are entirely cosmopolitan and can be found in urban locations all over the world.

crowgirl, 'where there's smoke there's fire'.
That plum tree may have a population of aphids (not necessarily an infestation) and warrants regular monitoring. It could be an opportunity to observe "biological control" in action.
There is a school of thought that when a plant is under 'attack' it sends out the biological equivalent of a '911 call' which brings in the predators.

That's right. i'd take the simple route and chop it down. I had to do the same with my greengage tree because it kept dropping its fruit on small animals. Next door's cat was knocked unconscious by one and I saw a sparrow killed by one once.

Thanks Jean001 and ronalawn82 - you've been very helpful. I'll get a gardener to check out my plumtree (the leaves are starting to curl, which suggests an infestation as you say) and then maybe the beetles, though good for the tree won't be needed. They kind of freak me out when I come into the house and have about 20 on me!

Dragonflykiller is obviously a crackpot. I will not be cutting down the tree.

it is a ladybug larvae

1. Soapy water Spraying ladybugs with soapy water is an effective way to get them out of your home. ...
2. Sweep or vacuum Experts suggest physically removing the ladybugs with a broom or vacuum. ...
3. Duct tape Because ladybugs bite when they're threatened, it's sometimes difficult to physically remove them from your house.

its a lady bug larva and if you find any orange things with 6 spots its a lady bug pupa

"Dragonflykiller is obviously a crackpot. I will not be cutting down the tree."

Lol!! An extremely outdated thread but I couldn't resist commenting on the OP's last thoughts 13 years ago. The though of a greengage plum knocking a cat unconscious I find very amusing :-) Just how flipping big are these plums?? Now if we were talking about monkey puzzle cones, an argument could be made for an injury from falling objects! But a plum?? Seriously??

Don't kill them. They are ladybugs They are the best insects you can have in your garden. And don't cut your tree either.