Those look like aphids to me...lots of them! I would spray it down with neem oil after wiping/hosing off as many as you can get off. As John has often said here, if you control the ants, you control the aphids. The ants farm the aphids. I do not have in-ground trees though, so I do not have much of a problem with either of those. Good luck!

Throughly hose that tree down...for several days until you get the situation under control.

In my experience, aphids are much smaller and translucent. Are there different types of aphids?

Yeah, I noticed that too, but perhaps yours are just bigger than the usual??? I don't know. Hopefully someone else can help you. However, regardless of what they are, hosing them down, scrubbing the leaves down the best you can, and spraying with some type of insecticidal soap or oil will not hurt and will likely solve your problem. Another member of this forum from Hawaii had something almost identical to yours and they were aphids, but I don't have enough experience to say for sure. Hopefully John or someone else will see this thread.

That may be scale also.

It is hard to see exactly from the pic, but now that I look again, they do look like possibly scale. The remedy is the same.

Thanks Jean for helping clarify! Well, I'm glad to know that the ladybug youngster eats them, but wasn't eating fast enough! I'm hosed down the branch and cleaned up the issue for now, but I'll have to buy some neem oil and spray down if the problem persists.

Thanks Jean. Always looking to learn!

Hi Salevene, what I have learned from an expert lemon citrus farmer is like what Laura already said here, "control the ants and you will control the aphids." As we speak, Terminix is here at my house and spraying my backyard for ants. He's being really careful not to touch my trees. I've been hosing off the aphids with water on a daily basis and adding neem oil on the weekends for about 3 weeks now and I see a HUGE difference.. I couldn't even find any to show the Termix guy.

Thanks figsinhawaii. But is there a natural way to control the ants? This is actually my 2nd infestation and I had to use a light pesticide the first time (I'm not going to let it fruit for at least another 6-12 months)....

Salevene, I never even noticed a problem but I had visitors for 10 days and because we were out and about every single day, I only watered my lemon tree at night once I settled down. Once my mom and company left after those 10 days, I went back out to tend to my garden and some areas of the lemon tree were just clustered with ants and aphids. I hadn't seen them before.. I'm assuming because during regular waterings, I would always to a spray down of the canopy anyway. It was SO gross. Many forum'ers gave me lots of advice, but what worked the best was a simple power hose to the tree canopy every single day and using the neem oil spray. I sprinkled cinnamon in the perimiter of the tree as well.

Here's a photo of both the ants and the aphids. I have a love/hate relationship with them. I hate them for obvious reasons and I (like?) them because I learned a lot from this experience and because if it wasn't for bringing up the topic of pests to a local nursery owner while window shopping for a new avocado tree, I wouldn't have my new Meyer lemon that he suggested : )

Salevene, I believe that figsinhawaii's recommendation is a natural way to control the ants and aphids. She uses water and neem oil which comes from a plant and is used by organic farmers. It is important that you do as she does which is to keep right on top of it with daily hosing and weekly neem spraying. After that, check frequently and carefully to make sure they don't come back.

Salevene, I typed my 2nd post before I noticed your question. Without using Terminix like I did, hosing and neem oil should work just fine as a natural method. As an extra natural touch, I added cinnamon but I'm not sure how effective that is as I'm sprinkling that on the grass and I don't even see the ants there. Since I only see them on my leaves, I know the spraying and the neem is effective. I was actually very happy when we went outside and there were no aphids or ants to show the Terminx guy on the tree : )