Yes, aphids, use an insecticidal oil to smother those, or on a plant like that you may be able to spray most of them off with a hose on certain nozzle settings. In your area aphid populations will increase quickly. Not too bad yet could change overnight to just too bad!

Are there ants on the tree as well? If they are farming the aphids they are the problem. Stop the ants (tanglefoot is good around trunk) and ladybugs will take care of rest...

Or try spraying them with soapy water ;)
Do not put too much soap though!!

Ladybug larva would already have to be present on the plant to control the current aphid population. I would not wait for that to occur for that particular plant.

Sorry didn't get alerts to all these. I don't see ants on the tree itself, we do have ants in a few places around the yard around the base of some citrus trees though. I'll try some soapy water and getting some ladybugs, haven't seen any around.

Getting ladybugs is fine, but it is a long-term solution as most purchased beetles fly off after release to distant yards. Once several people in the neighborhood release ladybugs a viable population of aphid-controlling ladybugs and larvae may develop over months and in succeeding years.