Jack Spaniard wasps (Hymenoptera: Vespidae) build their nests on thin branches, unfortunately usually at face level. They are not particularly aggressive, but if you disturb their nests they will sting you, sometimes more than once and they sting hard. So if your walking in the bush, be on the lookout.
I was told by a native Virgin Islander, and I witnessed the same, that if you take their nest they will not bother you. He carefully broke of the branch and threw it to the ground. The wasps swarmed around the nest, but didn’t come after us.
A Puerto Rican friend of mine will clap his hands over the nest squashing all the wasps and not get stung. My advise though is, “don’t try this at home, kids.”
Some people seem to react to the venom especially if you continue working or exerting themselves immediately after the sting so if you do get stung it’s probably a good idea to take it easy for a while. Usually it just hurts and that’s that.
They probably got their name because although the Spaniards had claimed all the “New World” to be theirs, other European nations established colonies on the smaller islands that Spain had ignored. Spanish warships would attack these colonies from time to time, I guess to make some sort of statement.