It is the nymph of either the assassin bug or leaf footed bug. I'm not good at telling them apart but I am going to guess leaf foot because there are a lot of them. I don't think assassin bugs congregate so much. The adults are easier to tell apart. Assassin bugs are good ones to have in your garden, they eat bugs you don't want. The leaf foots are bad guys.
You can google more info and pictures about them. I would do it, but I am doing this on my phone and it is complicated.