Is it a lump or a scale insect? Scrape it off, flip it over and see. Ants are usually attending where they can harvest some 'honeydew'. Usually from aphids but I'd still check and see if this "lump" is an insect.

Looks more like a lump. I scraped it off and it has some red powder like stuff inside.

Is it a widespread problem? All over the tree or on select branches? Do the lumps seem to be attracting the ants ?
I'm wondering if it might be an egg mass.
There are lots of info sites on Google regarding growing olives and the care of olive trees.

They seem to be on all the branches. I'd never seen them before and it doesn't seem to affect the tree. I'll keep an eye on them. I've done a google search...there's a lot of info out there.
Thanks for the help
Evelyn

OMG am I the only one who's completely blown away by the photograph??? How in the world did you get so close???

That lump is not shaped smooth like a black scale, that's why I think it's an egg mass or the bark has been sliced by an insect that deposits eggs under the bark and perhaps the black is ooze from the tree to heal the wound.

I'd google and find out more about growing olives and the diseases and insect pests of olive trees.

Just my two cents but that really looks like an ant harvesting nectar from a scale insect by stroking it with its antennae. I've never seen scale that look like that before but I have seen scale that are pretty much sedentary and do not move around on the stem. Scale bugs are such a bizarre group of insects that there is no way to categorize them easily.

I will check my olives to see if any black scale are on them. My European Olives are not liking the high heat and humidity so they would be prime candidates for an infestation. My black olive 'Arbequinea' is thriving. If anyone is looking to grow olives in a pot as a patio edible I highly recommend them. I treat mine just like a citrus tree. They do need to experience some cold in order to bloom but they don't like deep freezes or extended periods of sub freezing temps.

John
I think my olive is a Mediterranean type. It is in a container and I've never gotten olives from it. This is the first time I've seen anything like this. I have had scale before (on my Meyer Lemon) but it sure didn't look like this. It pops off and there's some kind of reddish powder in it. It really doesn't look like an insect.

I have one type of scale that i get on something (don't recall what off the top) that has reddish stuff inside, so don't rule out scale. I'm inclined to agree with john on this one. By the way, that is a really nice picture, too!

Evelyn, post your photo on the pest/insect forum and see if you get any response to identification. We might be getting sidetracked by the ant in the photo making us think this blob is an insect instead of a fungus or a tree wound.

I have the same thing on my olive tree has anyone figured out what it is?

When we were in humid TX I planted and olive tree there. Not problems at all. I order it from edible landscape. Now I garden in northern Spain and olives can take a lot more cold than you think. Just the olive oil quality is not good but it grow perfect. We have 200 years old olives in our street. Much more cold tolerant than citrus.

I have the same on my olive tree and now it on my Avo treas, does anyone know how to get rid of it?

This is likely the Black scale, Saissetia oleae. For more information see for instance at the UC IPM site here, or Google for other sources.